Entire Report - August 2012


National Overview

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.

Maps and Graphics

Temperature and Precipitation Ranks
U.S. Percentage Areas
More Information

National Overview:



August Extreme Weather/Climate Events

Supplemental August, summer, and January-August Information



Alaska Temperature and Precipitation:

  • Alaska had its 38th warmest August since records began in 1918, with a temperature 0.4°F (0.2°C) below the 1971–2000 average.
  • Alaska had its 39th coolest June-August since records began in 1918, with a temperature 0.7°F (0.4°C) below the 1971–2000 average.
  • Alaska had its 17th coolest January-August since records began in 1918, with a temperature 2.2°F (1.2°C) below the 1971–2000 average.
  • Alaska had its 33rd driest August since records began in 1918, with an anomaly that was 1.4 percent below the 1971–2000 average.
  • Alaska had its 24th wettest June-August since records began in 1918, with an anomaly that was 19.3 percent above the 1971–2000 average.
  • Alaska had its 28th wettest January-August since records began in 1918, with an anomaly that was 13.5 percent above the 1971–2000 average.

For additional details about recent temperatures and precipitation across the U.S., see the Regional Highlights section below and visit the Climate Summary page". For information on local temperature and precipitation records during the month, please visit NCDC's Records page. For details and graphics on weather events across the U.S. and the globe please visit NCDC's Global Hazards page.


Regional Highlights:

These regional summaries were provided by the six Regional Climate Centers and reflect conditions in their respective regions. These six regions differ spatially from the nine climatic regions of the National Climatic Data Center.

  • Northeast Region: (Information provided by the Northeast Regional Climate Center)
  • Temperatures during August 2012 averaged 1.7 degrees F (0.9 degrees C) above normal in the Northeast region. The monthly average of 70.0 degrees F (21.1 degrees C) was 1.1 degrees F (0.6 degrees C) warmer than August 2011 and 2.0 degrees F (1.1 degrees C) cooler than the warmest August in 1937. It was the warmest August since 2005, and the 20th warmest August since 1895. The northern states had the greatest temperature departures compared to normal, with Maine (+3.6 degrees F, 2.0 degrees C) and Vermont (+3.4 degrees F, 1.9 degrees C) leading the pack. This month was the 3rd warmest August in 118 years in Maine, the 7th warmest in New Hampshire and the 8th warmest in Massachusetts and Vermont. West Virginia (-0.1 degrees F, -0.1 degrees C) was the only state in the region with a temperature average that was cooler than normal. Climatological summer (June through August) also averaged warmer than normal the average temperature of 69.4 degrees F (20.8 degrees C) was 1.5 degrees F (0.8 degrees C) above normal. It was the 12th warmest summer in the Northeast since recordkeeping began in 1895. Each of the states in the region had summer temperature averages that were above normal. Departures ranged from 0.8 degrees F (0.4 degrees C) warmer than normal in West Virginia to 2.0 degrees F (1.1 degrees C) above normal in Delaware. It was the 3rd warmest summer since 1895 in Delaware.
  • August precipitation averaged 3.90 inches (99.1 mm), which was 100 percent of normal. For the most part, areas closest to the coast saw above normal rainfall, while inland regions were drier than normal. Maine (127 percent), Maryland (123 percent), Massachusetts (124 percent), New Hampshire (122 percent) and New Jersey (134 percent) were the states with positive precipitation departures. Departures in the remaining states ranged from 70 percent of normal in Vermont to 100 percent in Delaware. This was the first month since September 2011 that Delaware’s precipitation was not below normal. Summer (June through August) precipitation totals averaged below normal in the Northeast (95 percent) and in eight of the twelve states. The four wetter-than-normal states were New Hampshire (102 percent), Rhode Island (106 percent), New Jersey (108 percent, and Maine (126 percent). It was the 11th wettest summer since 1895 in Maine. Departures in the drier-than normal states ranged from 98 percent in Massachusetts to 77 percent in West Virginia, where it was the 22nd driest summer in 118 years. The US Drought monitor issued August 28, 2012 indicated that conditions improved slightly in Delaware, but the southern two thirds of the state were still in D1 (moderate) or D2 (severe) drought. In addition, slight improvements were seen in Maryland where most areas of D2 drought surrounding Chesapeake Bay on July 31 improved to D1 on August 28. Conditions in Massachusetts also improved the region of D1 drought in the western two thirds at end of July shrunk to just the southwestern portions of the state. A new area of abnormally dry conditions popped up in northern Vermont.
  • Lightning strikes during severe thunderstorms in August resulted in two fatalities. One was a spectator at the NASCAR race in Pennsylvania’s Pocono Raceway on the 5th. The other fatality occurred on the 15th in Long Branch, NJ when a man fishing with his son was struck by lightning.
  • Fruit crop growers in New York were beginning to quantify impacts of the roller coaster temperatures last spring. The September 2 Auburn, NY Citizen newspaper stated that “The last time farmers saw such devastating loss was in the early 40’s. This year’s forecast is the lowest production estimate since 1948, according to the USDA’s NASS.
  • For more information, please go to the Northeast Regional Climate Center Home Page.
  • Midwest Region: (Information provided by the Midwest Regional Climate Center)
  • August temperatures averaged to near normal across the Midwest. The first and last weeks of the month were above normal but the middle two weeks were below normal. Daily records followed the same pattern with mostly record highs on the first and last eight days of the month while mostly record lows were recorded from the 9th to the 23rd. The two cooler weeks in the middle of the month were a welcome break in a warm year. Summer temperatures in the Midwest were 1 to 3 degrees F (1 to 2 C) above normal but were near normal in eastern Kentucky. Year-to-date temperatures in the Midwest ranged from 2 degrees F (1 C) in eastern Kentucky to more than 5 degrees F (3 C) above normal in the western parts of the region.
  • August precipitation totals were above normal in south central Missouri and from western Kentucky, into southeast Illinois, across northern and central Indiana, and into northwest Ohio and southeast Michigan. The rest of the region was below normal with northern and central Missouri hardest hit at less than 25 percent of normal for August. Missouri rain totals failed to reach the 1 inch (25 mm) mark in many locations and with some failing to record even 0.50 inches (13 mm). Summer rainfall was below normal for most of the region. Summer totals were less than half of normal in parts of Missouri, Iowa, Illinois, southern Indiana, southwest Wisconsin, and southwest Minnesota. A few locations in the upper Midwest and Kentucky were slightly above normal for the summer. Year-to-date precipitation totals were less than 75 percent of normal for most of Missouri, Iowa, Illinois, Indiana, and western Kentucky. The upper Midwest had a mix of above and below normal totals for the year-to-date. The rainfall deficits for those areas ranged from 6 to 14 inches (150 to 350 mm).
  • The drought conditions in the Midwest saw both improvement and degradation during August. In southern Michigan, northern Indiana, and northwest Ohio, rains eased the drought but in Missouri and western Iowa conditions got worse through the month. While the percentage of the region in drought dropped from 71 percent to 65 percent in August, the areas in extreme (32 to 33 percent) and exceptional (5 to 7 percent) drought increased. The biggest improvements were in Indiana, Michigan, and Ohio while Iowa and Missouri had the largest degradations. August rains were too late for improvements in the corn crop conditions but there were some improvements in soybean conditions in locations that received above normal rains.
  • The remnants of hurricane Isaac moved into Missouri on the 31st and spread to the east. A handful of tornadoes were reported in Missouri and Illinois but damage was minor. One minor injury was reported in Morgan County, Illinois from severe thunderstorm winds. The rain was welcome across the drought stricken areas and it continued to spread across the southern Midwest into the first few days of September.
  • For details on the weather and climate events of the Midwest, see the weekly summaries in the Midwest Climate Watch page.
  • Southeast Region: (Information provided by the Southeast Regional Climate Center)
  • Mean temperatures were near normal to below normal across much of the Southeast region in August. The greatest departures were found across northern and extreme southern Florida, central sections of Alabama and Georgia, northern South Carolina, and the U.S. Virgin Islands, where monthly temperatures were between 1 and 2 degrees F (0.5 and 1.1 degrees C) below normal. Key West, FL, tied its lowest daily August maximum temperature of 81 degrees F (27.2 degrees C) on the 25th of the month (period of record 1872-2012). Over 200 daily low maximum temperature records were tied or broken in August across the Southeast, compared to only 30 high maximum temperature records. Elsewhere across the region, monthly temperatures were near normal, except along the North Carolina and Virginia coast and across northern Virginia, where monthly temperatures were between 1 and 2 degrees F (0.5 and 1.1 degrees C) above normal. Monthly temperatures were variable across Puerto Rico, with above normal temperatures across the northeastern part of the island and below normal temperatures across the southwestern part. The end of August marked the third warmest summer (June-August) on record in San Juan, PR, with a mean temperature of 84.3 degrees F (29.1 degrees C) (period of record 1898-2012). Across the rest of the Southeast region, mean summer temperatures were generally near normal to slightly above normal.
  • Precipitation in August was generally above normal across the Southeast. Widespread totals in excess of 10 inches (254 mm) were recorded along the Atlantic and Gulf Coasts, as well as across much of the Florida Peninsula, with some locations exceeding 20 inches (508 mm). Niceville, FL (period of record 1927-2012), located near Pensacola, and West Palm Beach, FL (period of record 1895-2012), recorded their wettest August on record with 21.05 inches (534.7 mm) and 22.66 inches (575.6 mm) of precipitation, respectively. Augusta, GA, recorded its second wettest August on record with 12.28 inches (311.9 mm) (period of record 1871-2012). Hurricane Isaac dropped between 6 and 10 inches (152.4 and 254 mm) of rain across a large portion of south Florida from the 26th to the 28th of the month. Several locations in Palm Beach County, FL, recorded over 10 inches of rain from the storm, including Vero Beach with 16.6 inches (421.6 mm). Rainfall from Isaac ranged from 2 to 5 inches (50.8 to 127 mm) across the western Florida Panhandle to as much as 14 inches (355.6 mm) along the Alabama coast. Prior to reaching the U.S. mainland, Isaac dropped between 4 and 8 inches (101.6 and 203.2 mm) of rain across Puerto Rico, with locally heavier amounts across the interior mountains. In addition to Isaac, there were other reports of locally heavy rainfall events across the Southeast. Roanoke Rapids, NC, recorded 11.5 inches (292.1 mm) of rain on the 25th of the month, which broke the previous all-time 24-hr precipitation total of 10 inches recorded during Hurricane Floyd in 1999 (period of record 1972-2012). As much as 8 inches of rain fell in the vicinity of Charleston, SC, resulting in major flooding of downtown streets. In terms of summer season precipitation, Tampa, FL, recorded 36.13 inches (917.7 mm), making it the second wettest summer in a record extending back to 1890.
  • Hurricane Isaac formed from a tropical wave east of the Lesser Antilles on the 21st of the month yet remained a tropical storm for much of its lifetime. Although the storm never made landfall in the Southeast region, its large size and slow movement resulted in numerous impacts across Puerto Rico, Florida, and Alabama. The heavy rain across Puerto Rico resulted in flash flooding and mudslides, which forced the closure of several roadways and bridges. Tropical storm force winds also brought down power lines, leaving thousands without power across the island. The combination of heavy rain and power outages also compromised municipal water systems, leaving thousands temporarily without clean or running water. The heavy rain across parts of south Florida resulted in flooding along major roadways and in neighborhoods and commercial districts, particularly in Palm Beach and Broward counties. Heavy surf, coastal flooding, and beach erosion were observed along the Florida and Alabama coasts. Mandatory evacuations were ordered for Baldwin and Mobile counties in Alabama as Isaac strengthened to hurricane status prior to making landfall along the Louisiana coast on the 29th of the month. Isaac also delayed the start of the Republican National Convention in Tampa, FL, a day from the 27th to the 28th of the month. Two deaths in the region have so far been confirmed from Isaac, one involving an automobile accident and one involving a jet ski accident in south Florida.
  • There were 439 reports of severe weather across the Southeast in August, with at least one report on 28 of the 31 days. There were 15 preliminary tornado reports, of which seven have so far been confirmed. On the 1st of the month, an EF-0 tornado touched down near Kiawah Island in Charleston County, SC. No damage was reported. On the 11th of the month, an EF-1 tornado was confirmed in the town of Stantonsburg in Wilson County, NC. Four homes sustained significant structural damage, one of which shifted approximately 20 feet (6.1 m) off of its foundation. A tornado touched down in Accomack County, VA on the 25th of the month, injuring an individual in a trailer park in the town of Melfa. There were several tornado reports associated with Hurricane Isaac between the 27th and 30th of the month. An EF-0 tornado was confirmed near Vero Beach in Indian River County, FL, with damage to as many as 95 homes. A water spout moved onshore and damaged six houses in the Tampa Bay area in Hillsborough County, FL, while two EF-0 tornadoes were confirmed in Jackson County and Holmes County, FL. Four separate tornadoes were reported across southern Alabama, including an EF-1 tornado that brought down several large trees and power lines and tore the roof off of a home in Geneva County.
  • For the second straight month, drought conditions improved or stabilized across the Southeast. By the end of August, over 60 percent of the region was drought-free, up from 40 percent at the end of July. Most notably, drought conditions were eliminated in Florida (the first time the State has been drought-free in over two years), and across a large section of Alabama. Additionally, improvements of one to two drought categories in the U.S. Drought Monitor were observed across South Carolina by the end of the month. There was a slight contraction of drought conditions across central Georgia; however, over one-third of the State remained in extreme (D3) or exceptional (D4) drought. By the end of the month, the harvesting of row crops was nearly complete (some delays were reported in areas that were particularly wet, especially along the Florida Panhandle) and most crops were reported to be in generally good condition across much of the region. The beneficial rain also helped livestock and pasture conditions, though some farmers were beginning to spray for disease and insects. Tobacco and cotton were also being sprayed in areas that were particularly wet.
  • For more information, please go to the Southeast Regional Climate Center Home Page.
  • High Plains Region: (Information provided by the High Plains Regional Climate Center)
  • For the first time since February of this year, there were widespread below normal monthly temperatures in the High Plains Region. Much of North Dakota, South Dakota, Kansas, and southern Nebraska had average temperatures which were up to 3.0 degrees F (1.7 degrees C) below normal. Interestingly, some of these areas have not had below normal monthly averages since last year, as the cooler areas in February were mainly in Colorado, Wyoming, and western Nebraska. For instance, the last time the majority of South Dakota had below normal temperatures was September of last year. Meanwhile, areas of Colorado, Wyoming, southern South Dakota, and western and central Nebraska had temperatures which were above normal. Departures were not high or low enough to break monthly records. However, there were still many daily records as temperatures dipped in the middle of the month and soared at the end of the month. One example was Academy 2 NE, South Dakota, which had a high temperature of 113 degrees F (45.0 degrees C) on the 30th. This beat out the old record of 101 degrees F (38.3 degrees C) and was the second highest August temperature on record (period of record 1898-2012). The highest August temperature of 115 degrees F (46.1 degrees C) was set on August 4, 1934. On the other end of the spectrum, there were also low temperature records. Lincoln, Nebraska had a low temperature of 44 degrees F (6.7 degrees C) on August 17th, which beat out the previous record of 46 degrees F (7.8 degrees C), set in 1943. August was a busy month for producers as drought damaged crops had to be chopped for silage or baled for hay in Nebraska, Kansas, and the Dakotas. The lack of feed and water caused the culling of herds to continue in Nebraska and Kansas. According to the USDA, by the end of the month 85 percent of all corn, 82 percent of all soybeans, 63 percent of all hay acreage, and 72 percent of all cattle were within an area experiencing drought conditions in the United States. This was a slight improvement from last month.
  • August was yet another dry month for the majority of the High Plains Region. A large expanse of the Region including Wyoming, eastern Colorado, the eastern and western sides of Kansas, most of Nebraska, central and southern South Dakota, and pockets of North Dakota had precipitation totals which were at the most 50 percent of normal. There were even areas of Wyoming, northeast Colorado, and the panhandle of Nebraska which received less than 5 percent of normal precipitation. Because of the lack of precipitation, there were new records set again this month. For instance Scottsbluff, Nebraska received no measurable precipitation and set a new record for driest August. The old record of 0.04 inches (1 mm) was set in 2001 (period of record 1893-2012). On average, Scottsbluff receives 1.30 inches (33 mm) of precipitation in August. Another location which had its driest August on record was Colorado Springs, Colorado which only received 0.12 inches (3 mm) of precipitation. This beat out the old record of 0.15 inches (4 mm) set in 1962 (period of record 1894-2012). The only areas of the Region which received much needed rainfall were pockets of central North Dakota, central and northeastern Kansas, far southeastern Nebraska, and a few pockets of western Colorado. These areas had precipitation totals ranging from 110 percent of normal to 300 percent of normal. The heavy rainfall improved drought conditions, however, at this point many of the crops will not benefit from the precipitation. According to the U.S. Drought Monitor, drought conditions worsened yet again this month across the High Plains Region. By the end of August, about 88 percent of the Region was under moderate (D1) to exceptional (D4) drought, with nearly 15 percent of the Region in the D4 designation. In contrast, at the end of last month, only 4 percent of the Region was in D4. Over the past month, the D4 areas that expanded include an area in central Nebraska that grew westward across the state and even into northeastern Colorado, an area in western Kansas that expanded all the way across the middle of the state to the eastern border, and an area in eastern Colorado that grew to include most of the southeastern corner of the state. By the end of the month over half the state of Kansas was in D4 drought. Extreme drought conditions (D3) also expanded in Colorado, Nebraska, South Dakota, and Wyoming. In addition, there was only a little over 1 percent of the Region that did not have any sort of drought or abnormally dry conditions (D0). According to the U.S. Seasonal Drought Outlook released August 16th, drought conditions were expected to improve in North Dakota, southwestern Colorado, and the northern half of South Dakota. Other areas of drought in the Region were expected to persist. Luckily, no new areas of drought were expected to develop.
  • Summer (June, July, and August) 2012 went down as one of the hottest on record for many locations in the High Plains Region. Even the locations that did not break records were very warm as every station had average temperatures which were above normal. The larger temperature departures occurred in eastern Colorado, eastern Wyoming, southern South Dakota, western and northern Nebraska, and pockets of Kansas where the departures from normal temperature ranged from 4.0-5.0 degrees F (2.2-2.8 degrees C) above normal. There were even a few pockets of northeastern Colorado, southeastern Wyoming, and southwestern Nebraska where temperature departures topped 5.0 degrees F (2.8 degrees C) above normal. Denver, Colorado was one of the record breaking locations with an average temperature of 76.3 degrees F (24.6 degrees C) which was 4.9 degrees F (2.7 degrees C) above normal. This easily beat the old record of 74.1 degrees F (23.4 degrees C) set in 1934 (period of record 1872-2012). Denver also set a new record for most days at or above 100 degrees F (37.8 degrees C) with 13. The previous record of 7 occurred in 2005. It was an overall dry summer for the Region and most locations ranked in the top 20 driest summers. Some locations set new precipitation records as well. Grand Island, Nebraska had its driest summer on record with only 2.37 inches (60 mm) of precipitation. This was 8.45 inches (215 mm) below normal and only 22 percent of normal precipitation. The old record of 2.87 inches (73 mm) was set back in the summer of 1940 (period of record 1895-2012). The impacts from the hot and dry summer have been numerous and many more will be realized as the summer is assessed. Just some of the impacts include widespread drought, crop damage and failure, low river levels, and fish kills.
  • For more information, please go to the High Plains Regional Climate Center Home Page.
  • Southern Region: (Information provided by the Southern Regional Climate Center)
  • August temperatures varied spatially across the Southern Region. In the east, Both Tennessee and Mississippi experienced average monthly temperatures that ranged from 0 to 2 degrees F (0 to 1.11 degrees C) below expected values. This was also the case for much of southeastern Louisiana and northeastern Arkansas. In the west, temperatures generally averaged 0 to 3 degrees F (0 to 1.67 degrees C) above normal, with the exception of the western Texas panhandle, where temperatures ranged from 3 to 5 degrees F (1.67 to 2.78 degrees C) above normal. The state average temperatures were as follows: Arkansas averaged 80.00 degrees F (26.67 degrees C), Louisiana averaged 81.80 degrees F (27.67 degrees C), Mississippi averaged 79.30 degrees F (26.28 degrees C), Oklahoma averaged 81.30 degrees F (27.39 degrees C), Tennessee averaged 75.50 degrees F (24.17 degrees C), and Texas averaged 83.70 degrees F (28.72 degrees C). For Texas it was the eighteenth warmest August on record (1895-2012), while Mississippi experienced its twenty-sixth coldest August on record (1895-2012). All other state ranking fell within the two middle quartiles.
  • August precipitation varied dramatically over the Southern Region, mostly in part to Hurricane Isaac, which drenched much of Louisiana, Mississippi, and southern Arkansas. Elsewhere, such as Texas and Oklahoma, conditions were quite dry. A small pocket of wetter than normal conditions occurred in north central Texas. In Tennessee, conditions were normal to slightly above normal in the central and eastern counties, while the western third of the state received below normal precipitation for the month. The driest part of the Southern Region was observed in southern Texas, where a majority of the stations there received only between 0 to 50 percent of normal precipitation. Hurricane Isaac's slow track over the south central portion of the region allowed for some rather impressive rainfall totals. Southern Mississippi average between 10 and 15 inches. In southeastern Louisiana, rainfall totals for the last week of the month ranged between 4 and 12 inches. Louisiana and Mississippi both experienced their second wettest August on record (1895-2012). Louisiana averaged a total of 8.47 inches (215.14 mm), whereas Mississippi averaged a total of 8.58 inches (217.93 mm). Arkansas experienced its twenty-second wettest August on record (1895-2012) with a state average precipitation total of 4.38 inches (111.25 mm). Other state precipitation totals include Texas with 2.07 inches (52.58 mm), Tennessee with 3.76 inches (95.50 mm), and Oklahoma with 2.80 inches (71.12 mm).
  • Despite heavy rainfall totals in the southeastern portion of the region, drought conditions remain relatively unchanged. This is in part due to the fact that much of the drought in this region is situated in areas outside of the reach of Hurricane Isaac. Conditions have deteriorated though most of Oklahoma, with almost the entire state being in extreme or exceptional drought. Elsewhere, the majority of Texas is still experiencing moderate to severe drought conditions. This is also the case in western Tennessee, where conditions were generally drier than normal for the month. In the case of Arkansas, much of the northern portions of the state are in exceptional to extreme drought conditions.
  • The main story of severe weather in the month of August for the Southern Region is that of Hurricane Isaac. Formed on August, 21, 2012 as a tropical storm, Isaac tracked slowly up the eastern Gulf of Mexico. On August 28, 2012 Isaac achieved hurricane status and made its first landfall between 6 and 7 pm central time near the mouth of the Mississippi River. At that point, much of southeastern Louisiana, southern Mississippi and southern Alabama were receiving heavy rainfall from the outer bands of the storm. Isaac then stalled just west of Plaquemines Parish. The storm made a second landfall near Port Fourchon, Louisiana in the early hours of August 29, 2012. A total of 5 fatalities were reported in Louisiana, and two fatalities were reported in Mississippi. As the storm tracked northwestward to Baton Rouge, much of southeastern Louisiana was under the grip of tropical storm force winds. According to WAFB news in Baton Rouge, approximately 800,000 Louisiana citizens lost power during the storm, with approximately 600,000 being in the greater New Orleans metropolitan area. Impacts of the storm on the Southern Region were plentiful. In Mississippi, a storm surge of 8.3 feet was reported in Hannock County. Wind gusts of 70 mph (112.65 km/h) were reported as far east as Gulfport. In Louisiana, the hardest hit area was Plaquemines Parish, where levees were overtopped. According to some officials, portions of the parish were inundated with as much as 12 feet (3.66 m) of water. Flooding was a major issue in many parts of the state including Laplace, Louisiana and Slidell, Louisiana. It is unclear at this point how many were impacted by the flooding, but initial reports suggest that thousands of flood insurance claims have already been filed in the wake of the storm. Storm surges in Louisiana varied from observations of around 6 feet (1.83 m) near Liberty Bayou at Highway 433 to 13.6 feet (4.15 m)in the vicinity of Lake Borgne. Damage in Baton Rouge was reported, with several homes being damaged by falling trees. However, by the time the storm reached the capital city, Isaac was weakened to a tropical storm. Over the next day, Isaac pushed north through southeastern Arkansas, where it dropped between 4 to 6 inches (101.6 to 152.4 mm) of needed rainfall in drought stricken areas.
  • For more information, please go to the Southern Regional Climate Center Home Page.
  • Western Region: (Information provided by the Western Regional Climate Center)
  • An active monsoon doused the southern Great Basin this month, while drier conditions dominated the Northwest, favoring development of numerous large and destructive wildfires. Average August temperatures ranged from 2-6 F (1-3 C) above normal over most of the West, with some locations recording their hottest August on record. Only the coastal regions of northern California and southern Oregon and a few other isolated locations averaged cooler than normal for the month.
  • A persistent upper level ridge and strong surface heating over the Great Basin and desert Southwest facilitated moisture transport into the area, supporting monsoon activity. The southern Great Basin saw most of the action, with numerous accounts of flash flooding, and several instances of record daily precipitation. Rainfall at the Las Vegas, Nevada airport totaled 2.31 in (58.7 mm), the second wettest August since records began there in 1937 (behind 2.59 in / 65.8 mm in 1957). Las Vegas also tied its record number of 12 thunderstorm days in August, set in 1955. Farther north, the airport at Tonopah, Nevada recorded 1.94 in (49.3 mm), its fourth wettest August in a record beginning in 1954. Many locations in the Southwest that receive a large portion of their annual precipitation during the summer monsoon (Las Vegas, Nevada and Phoenix, Yuma, and Tucson, Arizona) recorded above or near average August precipitation totals and are on track to meet the monsoon season (June-Sept) average at their respective locations. In contrast, New Mexico was dry in August, and statewide has experienced its driest 18 consecutive month period on record. By mid-August, 89% of the pasture and rangelands there were rated as poor, one of the highest percentages in the nation. Farther north, Reno Nevada experienced the third driest water year to date in its 75-year airport record.
  • The Pacific Northwest, which typically experiences low rainfall totals in August, was exceptionally dry this month. August 31st marked 42 days without measurable precipitation in Portland, Oregon, the 14th longest streak of this type on record. Billings, Montana experienced its driest first 8 months of the year since records began in 1934, only receiving 5.08 in (129 mm) in that time, 52 percent of average and below the previous minimum of 5.82 in (147.8 mm) in 1946.
  • Triple digit temperatures and record high minimum temperatures dominated much of the Southwest this August. Temperatures at Reno, Nevada airport averaged 79.0 F (26.1 C) for the month, 5.8 F (3.2 C) above normal and the hottest August on record since 1888. Reno reached 100 F (37.8 C) on 11 days, tied with 1970 and 2 days fewer than the 1972 record. In southern California, Lancaster recorded 23 consecutive days (July 29-August 20) of triple-digit F (over 37.8 C) heat, breaking the 2009 streak of 20 days. The average maximum temperature in Lancaster in August is 95.7 F (35.4 C).Various locations in southwest California hit daily high minimum temperature records on more than half the days in August. Further east, Phoenix, Arizona recorded its third warmest August minimum temperature of 84.9 F (29.4 C).
  • August (all month) Fires throughout the Northwest: Hot, dry, and windy conditions primed the region for wildfires this month. In conjunction with the fires, poor air quality prevailed in many areas, notably Idaho, Montana, and the northwestern Great Basin. The following are several fires that had significant impacts.
  • Washington: The Taylor Bridge Fire in central Washington burned 23,500 acres (9,510 hectares) along with 51 homes and 26 other structures. The fire did an estimated $8 million in damage.
  • Montana: The 19-Mile Fire, 10 miles southeast of Butte, Montana, consumed 14 homes and six structures over the last few days of August. At month’s end, 4,141 acres (1,675 hectares) had burned and containment stood at 64%.
  • Idaho: The Trinity Ridge Fire, near Featherville, Idaho, consumed 144,430 acres (58,448 hectares) and stood at 22% contained on [give the date]. The resort towns of Featherville and Pine were evacuated for a time due to the fire.
  • Nevada: On August 5 the state reported that 200,000 acres (80,972 ha) had burned, a total that had jumped to 800,000 acres (323,887 ha) three weeks later.
  • Northern California: The lightning-caused Ponderosa Fire in Shasta County destroyed seven homes, threatened 3,000 and caused an emergency declaration for the county. Further east near Quincy, CA, the Chips fire burned 75,217 acres (30,439 hectares) in August. That fire was 100% contained at the end of the month.
  • For more information, please go to the Western Regional Climate Center Home Page.

See NCDC's Monthly Records web-page for weather and climate records for the most recent month. For additional national, regional, and statewide data and graphics from 1895-present, for any period, please visit the Climate at a Glance page.


PLEASE NOTE: All of the temperature and precipitation ranks and values are based on preliminary data. The ranks will change when the final data are processed, but will not be replaced on these pages. Graphics based on final data are provided on the Temperature and Precipitation Maps page and the Climate at a Glance page as they become available.

Global Analysis

Contents of this Section:


August 2012 Selected Climate Anomalies and Events MapAugust 2012 Selected Climate
Anomalies and Events Map

Global Highlights

  • The average combined global land and ocean surface temperature for August 2012 was 0.62°C (1.12°F) above the 20th century average of 15.6°C (60.1°F). This is the fourth warmest August since records began in 1880.

  • The globally-averaged land surface temperature for August 2012 was the second warmest August on record, at 0.90°C (1.62°F) above average, while the globally-averaged ocean surface temperature was the fifth warmest on record, at 0.52°C (0.94°F) above average.

  • ENSO-neutral conditions continued in the eastern equatorial Pacific Ocean during August 2012. El Niño conditions are likely to emerge in September.

  • The average combined global land and ocean surface temperature for June–August 2012 was 0.64°C (1.15°F) above the 20th century average of 15.6°C (60.1°F), marking the third warmest June–August on record.

  • The globally-averaged land surface temperature for June–August 2012 was the all-time warmest June–August on record, at 1.03°C (1.85°F) above average.

  • The combined global land and ocean average surface temperature for January–August 2012 was the ninth warmest such period on record, at 0.56°C (1.01°F) above the 20th century average.


==global-temps-errata==

Introduction

Temperature anomalies and percentiles are shown on the gridded maps below. The anomaly map on the left is a product of a merged land surface temperature (Global Historical Climatology Network, GHCN) and sea surface temperature (ERSST.v3b) anomaly analysis developed by Smith et al. (2008). Temperature anomalies for land and ocean are analyzed separately and then merged to form the global analysis. For more information, please visit NCDC's Global Surface Temperature Anomalies page. The August 2012 Global State of the Climate report introduces percentile maps that complement the information provided by the anomaly maps. These new maps on the right provide additional information by placing the temperature anomaly observed for a specific place and time period into historical perspective, showing how the most current month, season or year compares with the past.

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Temperatures

In the atmosphere, 500-millibar height pressure anomalies correlate well with temperatures at the Earth's surface. The average position of the upper-level ridges of high pressure and troughs of low pressure—depicted by positive and negative 500-millibar height anomalies on the August 2012 height and anomaly mapAugust 2012 and the June–August 2012 height and anomaly mapJune–August 2012 maps—are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.

August

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Global Temperature Percentile Maps

Global anomaly maps are an essential tool when describing the current state of the climate across the globe. Temperature anomaly maps tell us whether the temperature observed for a specific place and time period (for example, month, season, or year) was warmer or cooler than a reference value, which is usually a 30-year average, and by how much.

The August 2012 Global State of the Climate report introduces percentile maps that complement the information provided by the anomaly maps. These new maps provide additional information by placing the temperature anomaly observed for a specific place and time period into historical perspective, showing how the most current month, season or year compares with the past.

Temperature Climatological Ranking

In order to place the month, season, or year into historical perspective, each grid point's temperature values for the time period of interest (for example all August values from 1880 to 2012) are sorted from warmest to coolest, with ranks assigned to each value. The numeric rank represents the position of that particular value throughout the historical record. The length of record increases with each year. It is important to note that each grid point's period of record may vary, but all grid points displayed in the map have a minimum of 80 years of data. For the global temperature anomaly record, the data does extend back to 1880. But not all grid points have data from 1880 to present. Considering a grid point with a period of record of 133 years, a value of "1" in the temperature record refers to record warmest, while a value of "133" refers to record coldest.

The Warmer than Average, Near Average, and Cooler than Average shadings on the temperature percentile maps represent the bottom, middle, and upper tercile (or three equal portions) of the sorted values or distribution, respectively. Much Warmer than Average and Much Cooler than Average, refer to the lowest and uppermost decile (top or bottom 10 percent) of the distribution, respectively. For a 133-year period, Warmer than Average (Cooler than Average) would represent one of the 44 warmest (coolest) such periods on record. However, if the value ranked among the 13 warmest (coolest) on record, that value would be classified as Much Warmer than Average (Much Cooler than Average). Near Average would represent an average temperature value that was in the middle third (rank of 45 to 89) on record.

More about climate monitoring…

The average global temperature across land and oceans during August 2012 was 0.62°C (1.12°F) above the 20th century average of 15.6°C (60.1°F) and ranked as the fourth warmest August since records began in 1880. Monthly global temperatures anomalies have been among the five highest for their respective months for five consecutive months, since April 2012. August 2012 marks the 36th consecutive August and 330th consecutive month with a global temperature above the 20th century average. The last below-average August temperature was August 1976 and the last below-average temperature for any month was February 1985. At the hemispheric scale, the Northern and Southern Hemisphere each also ranked as fourth warmest on record.

ENSO-neutral conditions continued during August across the central and eastern equatorial Pacific Ocean, with average sea surface temperatures in this region trending toward a three-month average of 0.5°C (0.9°F), the threshold for El Niño conditions. Spurred by the warming temperatures in the equatorial Pacific, the average global ocean temperature rose during August to 0.52°C (0.94°F) above average, tying with 2006 as the fifth warmest August on record. This is also the warmest anomaly for any month since July 2010, the month when the La Niña conditions that dominated from the latter half of 2010 through early 2012 first emerged. According to NOAA's Climate Prediction Center, El Niño conditions will likely emerge during September 2012.

Over land, the monthly average global surface temperature for August was 0.90°C (1.62°F) above the long-term average, tying with 2001 and 2011 as the second warmest August in the 133-year period of record, behind 1998. The Southern Hemisphere land tied with 2005 as the third warmest (0.86°C / 1.55°F above average) while the Northern Hemisphere land ranked seventh warmest (0.91°C / 1.64°F above average). The greatest anomalous warmth occurred across far eastern Canada, southern Greenland, central and southern Europe, western Kazakhstan, Japan, Western Australia, and Paraguay. Parts of Siberia were notably cooler than average.

  • The Bureau of Meteorology reported that the average August maximum (daytime) temperature across Australia was 1.49°C (2.68°F) above the 1961–1990 average, making this the sixth warmest August since national records began in 1950. Every state and territory across the country also reported above-average monthly maximum temperatures. However, while the country was warmer than average during the day, it was also colder than average at night. The August minimum (nighttime) temperature across Australia was 0.83°C (1.49°F) below average. The difference between the average maximum temperature and the average minimum temperature was the greatest on record for August and third highest for any month on record.

  • The average monthly temperature in New Zealand during August was 1.2°C (2.2°F) above the 1971–2000 average, making this an "unusually warm" August, according to NIWA. Northeast winds ushered in warm air that contributed to record or near-record high temperatures at 32 locations across the country.

  • Austria reported its fourth warmest August since national records began in 1767, with a temperature that was 1.9°C (3.4°F) above the 1971–2000 average. ZAMG, Austria's national meteorological agency, noted that the top three years were much warmer (3.7 to 3.8°C / 6.7 to 6.8°F above average) while this August falls largely in line with other years that ranked fifth through tenth (1.7 to 1.9°C / 3.1 to 3.4°F above average). The warm temperatures led to the third earliest complete snowmelt (August 19th) at the high elevation mountain station in Sonnblick. The two earliest snowmelts were each reported on August 13th in 1963 and 2003.

  • Spain reported its second warmest August since its records began in 1961, behind only August 2003, at 2.0°C (3.6°F) above the 1971–2000 average. According to AEMet, the warm temperatures were attributed in part to two separate heat waves that occurred during the month.

August Anomaly Rank
(out of 133 years)
Records
°C °F Year(s) °C °F
Global
Land +0.90 ± 0.18 +1.62 ± 0.32 Warmest 2nd 1998 +1.01 +1.82
Coolest 132nd 1912 -0.74 -1.33
Ties: 2001, 2011
Ocean +0.52 ± 0.04 +0.94 ± 0.07 Warmest 5th 1998, 2003, 2005, 2009 +0.57 +1.03
Coolest 129th 1910, 1911 -0.45 -0.81
Ties: 2006
Land and Ocean +0.62 ± 0.09 +1.12 ± 0.16 Warmest 4th 1998 +0.69 +1.24
Coolest 130th 1912 -0.51 -0.92
Northern Hemisphere
Land +0.91 ± 0.17 +1.64 ± 0.31 Warmest 7th 2010 +1.07 +1.93
Coolest 127th 1912 -0.96 -1.73
Ocean +0.56 ± 0.05 +1.01 ± 0.09 Warmest 8th 2005 +0.66 +1.19
Coolest 126th 1913 -0.57 -1.03
Land and Ocean +0.69 ± 0.13 +1.24 ± 0.23 Warmest 4th 2003, 2010 +0.77 +1.39
Coolest 130th 1912 -0.66 -1.19
Southern Hemisphere
Land +0.86 ± 0.13 +1.55 ± 0.23 Warmest 3rd 2009 +1.33 +2.39
Coolest 131st 1891 -0.89 -1.60
Ties: 2005
Ocean +0.49 ± 0.04 +0.88 ± 0.07 Warmest 7th 1998 +0.57 +1.03
Coolest 127th 1911 -0.48 -0.86
Ties: 2001
Land and Ocean +0.55 ± 0.06 +0.99 ± 0.11 Warmest 4th 2009 +0.66 +1.19
Coolest 130th 1911 -0.50 -0.90
Seasonal (June–August)


For the period June–August, the average global temperature across land and oceans was 0.64°C (1.15°F) above the 20th century average, making this the third warmest such period on record. It was the second warmest June–August in the Northern Hemisphere and ninth warmest in the Southern Hemisphere.

Considering global land surfaces only, June–August 2012 was record warm, at 1.03°C (1.85°F) above average. The highest anomalies occurred across parts of the Northern Hemisphere, including most of the contiguous United States and Canada, southern and eastern Europe, Kazakhstan, and eastern Siberia. Even with cooler-than-average temperatures in Alaska and northern Europe, the Northern Hemisphere observed its all-time warmest summer on record. And even with below-average temperatures across much of southern South America and northern and eastern Australia, the Southern Hemisphere observed its tenth warmest winter on record.

  • A warmer-than-average August, in combination with the hottest July and a warmer-than-average June, contributed to the third hottest summer on record for the contiguous United States, at 1.3°C (2.3°F) above average.

  • The average maximum (daytime) temperature for June–August (winter) across Australia was near normal, while the minimum (nighttime) temperature ranked as the third coolest on record, at 0.91°C (1.64°F) below average.

The average monthly global ocean temperature anomaly increased each month from June to August as ENSO-neutral conditions in the eastern equatorial Pacific Ocean continued to move toward potential El Niño conditions, making this the 11th warmest such period on record. Ocean temperatures were notably above average in the north central and north west Pacific Ocean, northeastern Atlantic Ocean and Labrador Sea, and cooler than average in the northeastern and central Pacific Ocean, the southern Atlantic Ocean, and the Indian Ocean near northern Australia.

June–August Anomaly Rank
(out of 133 years)
Records
°C °F Year(s) °C °F
Global
Land +1.03 ± 0.15 +1.85 ± 0.27 Warmest 1st 2012 +1.03 +1.85
Coolest 133rd 1885 -0.61 -1.10
Ocean +0.50 ± 0.04 +0.90 ± 0.07 Warmest 7th 1998, 2009 +0.58 +1.04
Coolest 127th 1911 -0.48 -0.86
Ties: 1997, 2001, 2002
Land and Ocean +0.64 ± 0.09 +1.15 ± 0.16 Warmest 3rd 1998 +0.69 +1.24
Coolest 131st 1911 -0.46 -0.83
Ties: 2005
Northern Hemisphere
Land +1.19 ± 0.15 +2.14 ± 0.27 Warmest 1st 2012 +1.19 +2.14
Coolest 133rd 1884 -0.70 -1.26
Ocean +0.53 ± 0.04 +0.95 ± 0.07 Warmest 8th 2005 +0.64 +1.15
Coolest 126th 1913 -0.54 -0.97
Land and Ocean +0.78 ± 0.12 +1.40 ± 0.22 Warmest 2nd 2010 +0.80 +1.44
Coolest 132nd 1913 -0.51 -0.92
Southern Hemisphere
Land +0.61 ± 0.12 +1.10 ± 0.22 Warmest 10th 2005 +0.95 +1.71
Coolest 124th 1891 -0.79 -1.42
Ties: 2001
Ocean +0.48 ± 0.04 +0.86 ± 0.07 Warmest 9th 1998 +0.59 +1.06
Coolest 125th 1911 -0.50 -0.90
Ties: 2010
Land and Ocean +0.50 ± 0.07 +0.90 ± 0.13 Warmest 9th 1998 +0.64 +1.15
Coolest 125th 1911 -0.52 -0.94
Ties: 2010, 2011

Year-to-date (January–August)

With the transition of La Niña early in the year to ENSO-neutral conditions, the average 2012 year-to-date global temperature for land and oceans combined has increased each month since February. For the year-to-date (January–August), the temperature was 0.56°C (1.01°F) above the 20th century average, marking the ninth warmest such period on record. The highest departures from average occurred across southern Greenland, northern Russia, and much of the United States and Canada, where record warmth for the period occurred. The coolest anomalies occurred over Alaska, the northeastern Pacific Ocean, central Asia, and most of Australia. Separately for the period, the average temperature above land surfaces was sixth warmest (0.95°C / 1.71°F above average), while the average sea surface temperature ranked as eleventh warmest (0.42°C / 0.76°F above average).

2012 year to date anomalies compared with five warmest years on record
Global Year to Date Temperature Anomalies

January–August Anomaly Rank
(out of 133 years)
Records
°C °F Year(s) °C °F
Global
Land +0.95 ± 0.21 +1.71 ± 0.38 Warmest 6th 2007 +1.12 +2.02
Coolest 128th 1893 -0.73 -1.31
Ocean +0.42 ± 0.04 +0.76 ± 0.07 Warmest 11th 1998 +0.57 +1.03
Coolest 123rd 1911 -0.50 -0.90
Land and Ocean +0.56 ± 0.10 +1.01 ± 0.18 Warmest 9th 1998, 2010 +0.70 +1.26
Coolest 125th 1911 -0.51 -0.92
Ties: 2006
Northern Hemisphere
Land +1.08 ± 0.26 +1.94 ± 0.47 Warmest 4th 2007 +1.29 +2.32
Coolest 130th 1893 -0.82 -1.48
Ocean +0.42 ± 0.05 +0.76 ± 0.09 Warmest 10th 2010 +0.57 +1.03
Coolest 124th 1910 -0.49 -0.88
Land and Ocean +0.67 ± 0.15 +1.21 ± 0.27 Warmest 6th 2010 +0.80 +1.44
Coolest 128th 1893, 1913 -0.52 -0.94
Southern Hemisphere
Land +0.61 ± 0.15 +1.10 ± 0.27 Warmest 8th 2005 +0.94 +1.69
Coolest 126th 1917 -0.73 -1.31
Ties: 2011
Ocean +0.43 ± 0.04 +0.77 ± 0.07 Warmest 11th 1998 +0.60 +1.08
Coolest 123rd 1911 -0.52 -0.94
Ties: 2007
Land and Ocean +0.46 ± 0.07 +0.83 ± 0.13 Warmest 12th 1998 +0.65 +1.17
Coolest 122nd 1911 -0.53 -0.95

The most current data August be accessed via the Global Surface Temperature Anomalies page.

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Images of sea surface temperature conditions are available for all weeks during 2012 from the weekly SST page.


Precipitation

The maps below represent anomaly values based on the GHCN dataset of land surface stations using a base period of 1961–1990. As is typical, precipitation anomalies during August 2012 and June–August 2012 varied significantly around the world.

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Global Precipitation Percentile Maps

Global anomaly maps are an essential tool when describing the current state of the climate across the globe. Precipitation anomaly maps tell us whether the precipitation observed for a specific place and time period (for example, month, season, or year) was drier or wetter than a reference value, which is usually a 30-year average, and by how much.

The August 2012 Global State of the Climate report introduces percentile maps that complement the information provided by the anomaly maps. These new maps provide additional information by placing the precipitation anomaly observed for a specific place and time period into historical perspective, showing how the most current month, season or year compares with the past.

Precipitation Climatological Ranking

In order to place the month, season, or year into historical perspective, each grid point's precipitation values for the time period of interest (for example all August values from 1900 to 2012) are sorted from driest to wettest, with ranks assigned to each value. The numeric rank represents the position of that particular value throughout the historical record. The length of record increases with each year. It is important to note that each grid point's period of record may vary, but all grid points displayed in the map have a minimum of 80 years of data. For example, considering a grid point with a period of record of 113 years, a value of "1" in the precipitation record refers to record driest, while a value of "113" refers to record wettest.

The Drier than Average, Near Average, and Wetter than Average shadings on the precipitation percentile maps represent the bottom, middle, and upper tercile (or three equal portions) of the sorted values or distribution, respectively. Much Drier than Average and Much Wetter than Average, refer to the lowest and uppermost decile (top or bottom 10 percent) of the distribution, respectively. For a 113-year period, Drier than Average (Wetter than Average) would represent one of the 38 driest (wettest) such periods on record. However, if the value ranked among the 11 driest (wettest) on record, that value would be classified as Much Drier than Average (Much Wetter than Average). Near Average would represent an average precipitation value that was in the middle third (rank of 39 to 75) on record.

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  • In the North Atlantic, Hurricane Isaac brought locally heavy rain to Hispaniola, Cuba, and parts of the southeastern United States, with southern Louisiana, where the storm made landfall, receiving up to 500 mm (20 inches) of rain.

  • In the western Pacific, a record three typhoons—Saola, Damrey, and Haikui—made landfall along China's mainland coast within a one-week period at the beginning of the month, each bringing heavy localized rainfall.

  • August was dry cross most of Australia, with the country as a whole reporting its fifth driest August since national precipitation records began in 1900, with monthly rainfall just 44 percent of average. The last month with an average national deficit this great was March 2009.

  • High pressure systems that led to heat waves in Spain also contributed to a dry August. Spain reported its third driest August since national records began in 1961, with average precipitation just above one-third of normal.

  • The South Asian monsoon season in India starts around the beginning of June and lasts through September. For the period June–August, India as a whole experienced rainfall that was 88 percent of average, with fairly similar deficits across the country's major regions, where precipitation ranged from 85 percent of average in northwest India to 90 percent of average in central India. Much of the country saw major deficits during June and July, while average rainfall during August, particularly during the last week, helped ease dryness in some areas. The weak monsoon season to date this year has produced drought across some major agricultural regions, which have seen localized rain deficits up to 28 percent of average.

  • It was also drier than average for the three month period across much of the central United States, from the Rocky Mountains to the Ohio Valley. One of the worst droughts on record gripped much of the central United States.

  • Due in large part to extensive wetness during June and much of July, the United Kingdom observed its second wettest summer in the 103-year period of record, and wettest since summer 1912.

Additional details on flooding and drought events around the world can also be found on the August 2012 Global Hazards page.

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References

Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.

Quayle, R.G., T.C. Peterson, A.N. Basist, and C. S. Godfrey, 1999: An operational near-real-time global temperature index. Geophys. Res. Lett., 26, 333-335.

Smith, T.M., and R.W. Reynolds (2005), A global merged land air and sea surface temperature reconstruction based on historical observations (1880-1997), J. Clim., 18, 2021-2036.

Smith, et al (2008), Improvements to NOAA's Historical Merged Land-Ocean Surface Temperature Analysis (1880-2006), J. Climate., 21, 2283-2293.

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Global Hazards

Please note: Material provided in this report is chosen subjectively and included at the discretion of the National Climatic Data Center (NCDC). The ability to report on a given event is limited by the amount of information available to NCDC at the time of publication. Inclusion of a particular event does not constitute a greater importance in comparison with an event that has not been incorporated into the discussion. Data included in this report are preliminary unless otherwise stated. Links to supporting information are valid at the time of publication, but they are not maintained or changed after publication.


Updated 21 Sep 2012


August 2012Wildfires sparked across southern Europe. read more August 2012North African regions fought famine. read more August 2012European countries sweltered under heatwave. read more August 10th–12thCold snap in Australia brought stiff winds and snow. read more August 2012Rains flooded central African nations. read more August 2012Torrential rains inundated the Far East. read more August 10thThirteen Bangladeshis killed by lightning strike. read more August 2012Eleven hurricanes kept the Oceans highly active. read more August 7thPolar blast brought snow to South Africa. read more August 2012Lessening sea ice eased Arctic passages. read more August 2012Drought disrupted wildlife habitats. read more



Drought conditions

World Meteorological Organization (WMO) leaders expressed concerns regarding global drought while advocating for national drought-management policies on August 21st in Geneva, Switzerland. Citing the impacts to food, water, health, and energy sectors, a summit to address water consumption and conservation issues will be convened in early 2013.

Prolonged drought effects were evidenced around the Northern Hemisphere during August. In the Sahel region of western Africa, the lack of rains resulted in extremely dry pasture lands and poor harvests, and served as a factor in worsening the hunger crisis within those countries. Humanitarian relief efforts were deployed to address famine and poor living conditions for an estimated 10 million people being affected, according to media reports. Likewise, similar water deficits, preceded by three successive seasons of drought across the Horn of Africa, adversely impacted several million people and contributed to the recent exodus of Somali residents where nearly 11,000 people have left the country since April 2012 to take up refuge in bordering countries. In Kenya, the Russian Federation donated wheat flour valued at $2 million U.S. dollars to aid nearly 3 million drought-affected poor residents and refugees.


U.S. drought intensification during August 2012
U.S. drought intensification
during August 2012
Source: NOAA Climate.gov

In the contiguous U.S., drought persisted and engulfed more than half the country. Dry conditions affected an estimated 164 million U.S. residents. As of the latter part of August, 1,692 of the nation's 3,143 counties were deemed as natural disaster areas due to drought. Cited by the U.S. Department of Agriculture (USDA) as the most severe and extensive drought in at least 25 years, the drought adversely impacted 65 percent of the U.S. cattle production and about 75 percent of corn and soybean production. As a relief measure for the American livestock producers, the USDA announced plans in August to purchase up to $170 million U.S. dollars of pork, lamb, chicken, and catfish for federal food nutrition assistance programs.


U.S. counties meeting disaster criteria in August 2012
U.S. counties meeting disaster
critera in August 2012
Source: USDA

Within the state of Hawaii, extreme drought forced reduction of the islands' cattle herds by about one-third due to lack of grass, according to media reports. At the Nature Conservancy's Niobrara Valley Preserve in northern Nebraska, drought and wildfires severely damaged its two pasture areas. Fire damaged about 11,000 acres, notably to those rangelands most accessible for public viewing of Great Plains bison. The lack of sufficient grazing area for the herds hastened the sale of more than 100 bison.

The August rains in Canada's Ontario province did not ameliorate the region's drought. According to media reports, Ottawa Valley farmers considered importing citrus pulp from Florida as a replacement feed for livestock, as the Canadian corn crops were severely damaged and hay prices have sharply risen during the drought. Fruit crops such as apples, which produced only one-fourth of the typical harvest, and next year's strawberries were in jeopardy.


Smoke Plumes from Grecian Wildfires on 18 August 2012
Smoke Plumes from Grecian
Wildfires on 18 August 2012
Source: NASA Earth Observatory

Wildfires scorched regions around the Mediterranean Sea and southeastern Europe. According to media reports, 30 wildfires blazed across southern Italy and close to 900 people were evacuated near Sicily's Zingaro National Park, a reserve of 4,000 acres. A forestry worker died while battling the flames. Much of Italy has experienced drought for several months. Nearly 600 wildfires charred parts of Greece, forcing evacuations while injuring two persons and destroying over 3,000 acres near Megalopoli while a major blaze on Chios destroyed at least 37,000 acres and rendered severe losses of the world's only mastic groves. The mastic gum industry yields an estimated annual revenue of $3.75 million U.S. dollars in Greece. In southern Bulgaria, multiple wildfires raged—one fire near Krumovgrad forced evacuations of residents and another fire near Belitsa destroyed about 988 acres—while close to 300 brush fires burned across the country. Thunderstorms brought relief to Bulgarian firefighting efforts by mid-month.

According to media reports, a brushfire on August 27th in Queensland, Australia, caused a power loss to 450 customers when two utility poles were burned near Cloncurry. The wildfire, which scorched over 18,500 acres, caused a brief stretch of highway to be closed and forced a temporary evacuations of two homes as well as 20 persons from a local hospital. A New South Wales fire initially intended as a prescribed burn within the Bowen Mountain National Park was spread by strong winds on August 30th. The 7,400-acre blaze encroached to within about 2 km (one mile) of a residential area.


Night view of western U.S. fires on 17 August 2012
Night view of western U.S. fires
on 17 August 2012
Source: NASA Earth Observatory

Wildfires burned fiercely in the northwestern U.S. during August. In the state of Washington, the massive Taylor Bridge Fire destroyed more than 60 homes, scorched 28,000 acres, and forced evacuation of over 400 homes, according to media reports. In Idaho, the death of a firefighter occurred from being struck by a falling tree during efforts to battle the Steep Corner blaze. Please see NOAA's Wildfires page for additional information.

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Extreme Temperatures

Intense high pressure systems tracking across northern Africa into the Mediterranean countries prolonged the heatwave for Central Europe in August. During the first week of the month, over 180 people in Romania received medical treatment for heatstroke while Serbia experienced temperatures soaring up to 46.0°C (114.8°F). On August 7th the daily maximum temperatures reached 37.0°C (98.6°F) in Rome and 44.0°C (111.2°F) in Agrigento, Sicily, according to media reports. At mid-month, heat advisories were issued for six provinces across south-central France as temperatures hit the triple digits while wildfires erupted in the country's southwestern region. For parts of France and Germany (also hitting triple digits), such extreme heat had not occurred since the 1920s. In Italy, to help relieve dehydration and potential heatstroke, the animals at the Rome Bio-Park were treated to iced foods in August. Giant ice cubes containing raw meat were provided to the tigers, lions, and leopards. Primates received bamboo canes filled with frozen yogurt and watermelon. In late August, the Balkans continued to swelter and temperatures topped 41°C (106°F) on August 26th at Loznica, Serbia.

Australia's extreme temperatures were themselves an extreme, as the nation experienced net warmth during August. While maximum temperatures stayed above-average for the month (6th warmest August), the minimum temperatures dipped (14th coolest August), based upon Australian records since 1950. Consequently, the country's diurnal temperature range anomaly of 2.32°C (4.18°F) constituted the highest on record for an August month. Western Australia recorded its second-warmest August since 1950, with the two regions of Pilbara and Kimberly having their record-high August maximum temperatures. A cold front passage dropped nighttime temperatures to below freezing in the Blue Mountains west of Sydney on August 9th as light snow fell, according to media reports. Tragically, at least four deaths resulted from multiple house fires coincident with the mid-month cold snap in New South Wales. Authorities suspected unattended heating applicances as being a likely cause of the fires.

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Heavy rainfall and flooding


Blended estimates of African rainfall for August 22–28, 2012
Blended estimates of African
rainfall for August 22–28, 2012
Source: NOAA

During August, several parts of the world dealt with severe damages and death rendered by monsoonal rains and flooding. Nations in Africa and southern Asia were notably impacted.

Above-average rainfall across east-central Africa during the first week of the month produced localized flooding causing displacement of at least 15,000 people throughout Sudan. According to media reports, 32 deaths from floods in Sudan have occurred since mid-June. To the west, torrential rains destroyed homes, displaced several hundred people, and flooded farmlands in Nigeria at mid-month, according to media reports. The Nigerian Red Cross provided assistance. By month's end, 5 fatalities and 19 injuries within Nigeria resulted from additional flooding around Katsina.

Monsoons across India and Myanmar caused widespread destruction. In northern India, flash floods and landslides resulted in the loss of at least 28 lives with 7 persons missing and 8 others injured, according to media reports. Close to 500 travelers were stranded when a bridge near Uttarakhand collapsed and over 400 Indian families along local rivers were evacuated. Indian officials estimated the property damage at $100 million U.S. dollars. Heavy rains resulted in evacuation of more than 85,000 residents within Myanmar and inundated over 600,000 acres. In northeastern Myanmar, flash flooding on August 19th—deemed the worst in 54 years—claimed one life and two persons were missing near the city of Lashio, according to media accounts. Homes were swept away and partially-submerged vehicles were abandoned on the main highway while around 200 residents stayed in emergency shelters.

China's eastern and central provinces endured the rampant effects of a succession of typhoons during August. Nine lives were lost and four persons were missing within the northeastern province of Liaoning where heavy flooding caused economic losses in excess of $3.7 million U.S. dollars, according to media reports. The deluge which developed in the aftermath of Typhoon Damrey, dropped up to 220 mm (8.66 inches) during August 3rd–4th upon the area, and adversely impacted at least 1.4 million people. Over 138,000 residents were evacuated, while more than 27,000 homes were ruined and nearly 173,000 acres of crops were damaged as a result of the floods. Notable disruption to three major railways occurred as sections became submerged or collapsed. In the country's northeastern province of Hebei, an eroded section of the Great Wall collapsed on August 6th as a result of torrential rains, in the area where about 2.3 million people were impacted by flooding and over 150,000 residents were evacuated. Days of continuous rains in central China during August 4th–6th rendered deadly destruction within Hubei province. Flooding caused at least 25 fatalities, the loss of more than 46,000 homes, shortages of drinking water for 50,000 people, and property damages with an estimated value of $94 million U.S. dollars, according to media accounts. The heavy rains ensuing from Typhoon Saola also disrupted traffic, power supplies, and telecommunications for close to 30,000 residents. The Red Cross Society of China distributed more than 20,000 mosquito net and clothing items to the affected communities. In the province of Gansu, several cultural relics housed in a Chinese museum were damaged during the early August rains. In Yunnan province, a mudslide claimed the life of one person and injured 40 residents, while inflicting serious destruction—approaching $15 million U.S. dollars in costs—across an area of about 475 acres. According to media reports, over 80 homes were lost, nearly 500 livestock perished, numerous roads and bridges were destroyed, while three power plants were damaged within Eryuan county.

Later in the month, heavy rains fell over China's southern provinces of Hunan and Guangdon with areas receiving as much as 300 mm (11.8 inches) in 24 hours. The media reported that at least two deaths resulted as flash flooding and mudslides toppled at least 106 homes and forced evacuation of over 800 people. Additional rains across the Hubei province during August 20th–21st, destroyed another 400 homes and forced evacuation of more than 1,800 people.


Philippiines Rainfall Total of Jul 25–Aug 9, 2012
Philippines Rainfall Total
of Jul 25–Aug 9, 2012
Source: NASA Earth Observatory

Monsoon rains—exacerbated by Typhoon Haikui—inundated the Philippines in early August and brought devastation to almost 1.2 million people, according to media reports. At least 23 persons died in flash flooding and landslides around Manila. More than 780,000 area residents were forced to evacuate after 11 straight days of monsoon downpours. On August 8th, the area received 54.7 mm (2.15 inches) in a single hour.

In the U.S., flooding in northwest Alaska delayed the opening of a school in the village of Kivalina where mud and landfill debris contaminated the local drinking water. The area received 210.1 mm (8.27 inches) of precipitation—more than half its annual rainfall—during the month of August. The Wulik River which flows near the village crested at 4.66 m (15.3 ft) on August 16th, marking the river's highest level since measurements began in 1985. Also, pipes which transport the water supply to storage tanks for the village were damaged during the river's surge.

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Severe Storms

Heavy showers with thunderstorms across Britain produced torrential rainfall and funnel clouds on August 5th. According to media accounts, up to 30 mm (1.18 inches) of precipitation fell within an hour in parts of the region. Flash flooding and landslides forced evacuations of residents while impeding transportation on railways and roads.

On August 10th, lightning struck a microphone atop a tin structure in a northeastern Bangladesh village electrocuting 13 worshippers and injuring 15 other persons. About 35 people were attending temporary services at the converted shelter, instead of the area's concrete-roofed mosque to which access was hindered after heavy rains had swollen the nearby river.

Large hail—deemed the size of chicken eggs—caused injuries to more than 20 people in the southern Kemerovo region of Russia on August 14th, according to media accounts. The hail shower produced stones of up to 7.0 cm (2.75 inches) which pelted glass and metal surfaces, inflicting extensive damage to at least 60 vehicles as well as rooftops and local real estate. An abrupt temperature drop from 32°C (89.6°F) to 16°C (60.8°F) was attributed as triggering the violent summer-time storm.


U.S. Storm Reports for 04 August 2012
U.S. Storm Reports
for 04 August 2012
Source: NOAA Storm Prediction Center

In the U.S., a severe storm system crossing through the Great Lakes Region on August 4th was accompanied by lightning and large hail. Tornadic winds overturned lightweight vehicles and felled trees which disrupted power for over 12,000 customers in northwest Indiana and southwest Michigan, according to media reports. More severe weather rumbled in the Middle Mississippi and Ohio Valleys region at mid-month, bringing strong winds and hail to Missouri, Illinois, Indiana, Kentucky, and Tennessee. A funnel cloud was spotted over Lake Michigan on August 20th, where at least nine waterspouts were spied in the preceding days. Tornadoes swept through five counties in eastern Missouri and western Illinois on August 31st as drenching rains from Hurricane Isaac spread over the region.

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Tropical Cyclones

Eight tropical cyclones developed in the Atlantic Basin during August, of which five reached hurricane strength. Several of the storm systems were associated with fatalities. Please visit NOAA's Hurricanes and Tropical Storms page for detailed information.


Hurricane Ernesto neared Yucatan Peninsula on 07 Aug 2012
Hurricane Ernesto neared
Yucatan Peninsula on 07 Aug 2012
Source: NASA Earth Observatory

Hurricane Ernesto (Aug 1st–10th) originated east of the Lesser Antilles and made two landfalls in Mexico—first along the southern Yucatan Peninsula near Mahahual (August 7th) and then along the Gulf coast near Coatzacoalcos (August 9th). The Gulf region received rainfalls between 177–273 mm (7–10 inches) within 24 hours and 12 fatalities were attributed to the storm, according to media reports. Remnants of Ernesto provided the genesis of an Eastern Pacific cyclone, Tropical Storm Hector later in August.


Hurricane Gordon neared the Azores on 19 Aug 2012
Hurricane Gordon neared the Azores
on 19 Aug 2012
Source: NASA Earth Observatory

Tropical Storms Florence (Aug 4th–6th) and Joyce (Aug 22nd–24th) followed similar tracks, moving westward over the open ocean after spawning off the coast of Africa. Hurricane Gordon (Aug 15th–20th) initially traveled westward from Africa, before reversing course to the northeast and depositing drenching rains upon the Azores. The paths of Hurricanes Kirk (Aug 28th–Sep 2nd) and Leslie (Aug 30th–Sep 11th) also began near Africa, but each took a northward turn, with Leslie making landfall in Canada, while Kirk remained at sea.

According to media reports, two persons perished and two others were missing in Trinidad on August 10th as a result of landslides triggered by heavy rains associated with Tropical Depression Seven, predecessor of Tropical Storm Helene. Close to 1,000 homes were flooded and many roads damaged, the initial estimate of losses was over $17 million U.S. dollars. The system gained strength in the Bay of Campeche to emerge as Tropical Storm Helene (Aug 17th–19th) and made landfall on August 18th near Tampico, Mexico. Heavy rain fell across the Mexican states of Veracruz, Tamaulipas, and San Luis Potosi, while compounding adverse conditions for the 10,000 residents left homeless from Ernesto's earlier passage. Meanwhile, the country's fortified oil installations in the Gulf of Mexico remained intact.


Hurrican Isaac rainfalls over Caribbean on 24 Aug 2012
Hurrican Isaac rainfalls over
Caribbean on 24 Aug 2012
Source: NASA Earth Observatory

Hurricane Isaac (Aug 21st–30th) made landfall in Haiti, then Cuba, and two landfalls in the U.S.—both within the state of Louisiana—striking in Plaquemines Parish on August 28th, then near Port Fourchon on August 29th. According to media accounts, strong winds and heavy rains of up to 200 mm (7.87 inches) lashed the Caribbean with deadly results. In Haiti, 19 people perished, 6 persons were missing, 355 homes were destroyed, and nearly 15,000 people were evacuated because of the storm. Five persons died in the Dominican Republic where around 13,000 residents were evacuated, and close to 25,000 residents were evacuated in Cuba during Isaac's passage.


Hurricane Isaac's strengthened in Gulf of Mexico on 28 Aug 2012
Hurricane Isaac strengthened
in Gulf of Mexico on 28 Aug 2012
Source: NASA Earth Observatory

The large size of the storm, roughly 400 km (248 mi), was conducive to the substantial storm surge of as much as 3.6 m (12 ft) along the affected U.S. coastal areas. Heavy rainfalls occurred across the Lower Mississippi Valley and Atlantic Coast states, where Isaac inundated New Orleans with 510 mm (20.08 inches) of precipitation by August 31st. In the U.S. at least seven deaths resulted during the flooding, while nearly 60,000 residents were evacuated, and over 900,000 homes lost power. The slow-moving system caused extensive damages across Louisiana, Mississippi, and Arkansas, where restoration costs of electrical facilities were estimated between $400 million and $500 million U.S. dollars, according to media reports.


East Pacific tropical cyclones satellite view on 10 Aug 2012
East Pacific tropical cyclones
satellite view on 10 Aug 2012
Source: NASA

In the Eastern Pacific, two hurricanes and one Tropical Storm developed along the western coast of Mexico. Although none posed a significant threat to land, the powerful systems illustrated the extreme intensity exhibited by tropical cyclones. Hurricane Gilma (Aug 7th–11th) formed high, cold cloud tops of -52°C (-63°F) while strengthening on August 9th. Tropical Storm Hector (Aug 11th–17th) produced rains at sea of up to 50 mm (2 inches) per hour on August 14th. Hot towers preceded the intensification of Hurricane Ileana (Aug 27th–Sep 2nd).


Typhoon Haikui lashed China coast on 07 Aug 2012
Typhoon Haikui lashed China
coast on 07 Aug 2012
Source: NASA Earth Observatory

The Western Pacific continued to be active during August with four deadly typhoons, a tropical storm, and two depressions. Typhoon Haikui (Aug 1st–10th) which developed over the Philippine Sea, made landfall on the eastern coast of China on August 8th. In the Philippines, at least 19 deaths occurred from landslides, drowning, and electrocution while four persons were injured and three others were missing. Media reports indicated that flooding within the island nation caused by Haikui was the worst since 2009 and impacted nearly 2 million Filipinos during August. In China, torrential rains from the third typhoon within a week to the area, impacted over six million residents of the Shanghai, Anhui, Jiangsu, and Zhejiang provinces, according to media accounts. The deaths of at least six people and injuries to seven others were attributed to the storm, as flooding contaminated drinking water, caused transportation delays, and disrupted power to nearly 400,000 Chinese households. Over 7,500 homes and approximately one million acres of croplands were destroyed, resulting in damages estimated at $1.5 billion U.S. dollars.

Typhoon Helen (a.k.a. Kai-tak; Aug 12th–18th) which swept across the northern Philippines, made another landfall in southeastern China's Leizhou Bandao Peninsula, then a final landfall along the coast of northeast Vietnam. Flooding and landslides associated with the typhoon claimed over 40 lives, according to media reports. In the Philippines, 10 deaths and 17 injuries resulted, 42 homes were damaged, and over 3,400 residents were impacted. At least three of the fatalities occurred in China, where 4,200 homes were lost and flood-related damages approached an estimated $262 million U.S. dollars. More than 500,000 Chinese residents were evacuated, over 51,000 fishing boats were recalled to port, and train services were disrupted because of the storm. In Vietnam, strong winds and heavy rains imposed by the typhoon claimed at least 31 lives, damaged close to 12,000 homes, and flooded nearly 57,000 acres of crops.


Typhoon Bolaven neared Korean Peninsula on 28 Aug 2012
Typhoon Bolaven neared Korean
Peninsula on 28 Aug 2012
Source: NASA Earth Observatory

Typhoon Bolaven (a.k.a. Julian; Aug 17th–29th), a powerful storm originating southwest of Guam and making landfall in North Korea, caused at least 88 deaths and widespread devastation within the Far East. As the storm passed to the west of Japan on August 25th around 66,500 households lost power and five persons were injured. Damages were extensive to the Korean Peninsula as torrential rains disrupted power and flooded homes, roads, and farmlands. At least 15 deaths occurred in South Korea, including eight fishermen when boats were capsized while as many as 200,000 residents lost utilities. In North Korea, 59 fatalities resulted from the storm which left over 26,000 residents homeless, more than 127,000 acres flooded and the roof of a large power station destroyed by strong winds and rain. In Russia's Khabarovsk Region, where heavy rains brought relief to the Russian wildfires, the winds caused power losses for about 4,000 residents.

Typhoon Tembin (a.k.a. Igme; Aug 17th–30th) brought more drenching rains to the Korean Peninsula within days of Bolaven, after making a loop over Taiwan. Ten fatalities were attributed to the storm. Tembin inundated Taiwan with more than 500 mm (19.7 inches) during the initial pass on August 24, while leaving 5 people injured, and over 50,000 residents without power. Effects of two passages by Tembin caused flooding in the northern Philippines which resulted in eight deaths and impacted over 5,000 residents as of August 27th. At least two persons perished and three people were injured when Tembin slammed South Korea on August 30th with intense rains of up to 200 mm (7.87 inches) per hour, according to media reports.

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Severe winter weather

Cold air advection associated with a strong surface high brought extreme weather to South Africa in early August. Heavy snowfall and rain in the eastern mountainous areas disrupted power for about 70,000 residents while closing roads and high-altitude passes. Snow—a rarity in the city—fell lightly in Johannesburg on August 7th, enough to cover rooftops and create slippery roads while flurries reached Pretoria, the capital of South Africa. According to media accounts, Johannesburg has received snow only 22 other days in the last 103 years. Over 300 people evaded the below-freezing temperatures by spending the night in emergency shelters. More cold, wind, and rain battered the western side of the country again the following week, resulting in Port Elizabeth having its second wettest winter with 424 mm (16.7 inches) of precipitation occurring by August 13th as based on rainfall records kept since the 1960s and followed three years of drought and stringent water restrictions.

According to media accounts, strong winds of up to 106.0 km/hr (65.8 mph) ushered in polar air to southeastern Australia, as a strong low pressure system brewed over the Tasman Sea. In Sydney, train and ferry services were disrupted, roofing was blown off, and the many uprooted trees downed power lines, leaving over 18,000 residents without power on August 10th as a result. Blustery winds produced rough surf and grounded boats along the nearby coasts. Cloudiness and cold accompanied the front as less than four hours of sunshine limited the daily maximum temperature at 14.9°C (58.8°F) while the stiff wind chill compounded its bitterness and the minimum temperature dipped to 7.6°C (45.7°F). Meanwhile, up to 50 cm (about 20 inches) of new snowfall dropped over two days at the Perisher, a ski area located in Australia's Snowy Mountains, which lies approximately 500 km (310 mi) to Sydney's southwest. Another bout of strong winds on August 16th–17th contributed to Sydney's having its windiest August since 2001, and left around 13,000 Sydney households without power.

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Polar Events and Sea Ice

In early August, sailors observed a granite-encrusted iceberg at 22 km (12 nautical miles) northeast of Point Barrow, Alaska, according to media reports. The iceberg's striations and rocks suggested its origin as being from a glacier located within the northeastern Canadian Arctic Islands. Recent melting of Arctic sea ice may have facilitated the unusual iceberg's drifting into near-shore waters.

Summer Cyclone over the Arctic on 07 August 2012
Summer Cyclone over the Arctic
on 07 August 2012
Source: NASA Earth Observatory

In the following days, a strong low pressure system lingered over the North Pole to create perilous boating conditions for a team of rowers attempting to cross the Arctic Ocean from Canada to Russia. The storm was deemed uncommon for its unseasonable presence and its unusually low central pressure, sinking to 964 millibars on August 6th.

The Chinese icebreaker, Xue Long (a.k.a. Snow Dragon) made port in Iceland on August 16th after making a six-week passage via the Northern Sea Route through the Arctic—a first time in Chinese history. Using the Arctic route for the 15,000 km (9,320 mi) scientific expedition between China and Iceland was about 40 percent less in distance than to traverse through tropical seas, according to media accounts. The two countries recently expanded cooperative efforts for geothermal energy development. The expedition goals were to study changes in Arctic ecosystems and the related impacts on Chinese climate.

Arctic sea ice extent on 31 August 2012
Arctic sea ice extent
on 31 August 2012
Source: NSIDC

On August 26th, the Arctic sea ice was observed at its smallest extent on record (previously set in 2007) and covered 4.10 million square km (1.58 million square mi). The National Snow and Ice Data Center (NSIDC) reported that sea ice extent reached a lower minimum of 3.69 million square km (1.4 million square mi) as of August 31st. By September 16th, the sea ice extent dropped to 3.41 million square km (1.32 million square mi), constituting the lowest seasonal minimum extent in the satellite record since 1979. The rapid shrinkage was deemed by scientists as part of the larger pattern of a changing Arctic. Please visit NOAA's Global Snow & Ice page for additional information.

Meanwhile, leveraging the lack of sea ice, another team's attempt to navigate the Northwest Passage by sailboat was underway, according to media reports.

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Ecosystems Impacts

A revolutionary method to quickly assess drought tolerance of plant leaves using osmometry resulted from collaboration efforts between U.S. and Chinese scientists. By measuring the turgor loss point (the point at which leaf cells reach critical dehydration), scientists can quickly predict the dryness of the plant's ecosystem within several minutes versus several days as previously needed. Through assessment of the drought vulnerabilities, threats to plants can be better understood and conservation efforts improved.

Greater Sage-Grouse in North America
Greater Sage-Grouse
in North America
Source: US Bureau of Land
Management

According to media accounts, birds have been impacted by drought and wildfires. In Europe, the uncommon sighting in Ireland of a Pallid Harrier—indigenous to Asiatic Russia, Kazakhstan and northwest China, occurred during August. Bird-watching enthusiasts observed the rare bird species breeding in Finland, Portugal, Spain, and France during the past 18 months, following three successive summers of wildfires which have disrupted its Northern Asia steppe grasslands habitat. In western North America, a lack of natural wildflowers has impacted the annual migration patterns for hummingbirds and other pollinators as sources of nectar were scarce. A "nectar corridor" which extends from southwestern Mexico and northward to the Intermountain West of the U.S. and Canada also nourishes migratory bats, doves, and butterflies. Wildfires in California have destroyed the prime sage-grouse habitat in Lassen County and prompted cancellation of the 2012 hunting season upon the bird. The sage-grouse are a candidate for listing under the U.S. federal Endangered Species Act.

Rainfall deficits across southern India provided favorable conditions for the white stem borer, a deadly pest of arabica coffee plants. Damages to the region's coffee plantations were severe as a result of from the insect's larvae having killed young plants and the drought having reduced the size of the coffee beans.

Drought may have factored in the resurgence of anthrax outbreaks occurring in North America. The bacteria—which can lie dormant in soil for decades—reacts to harsh conditions by producing more spores. More than 100 animal deaths from anthrax occurred in the U.S. in August, and an unusually high number of bison succumbed to the disease in Canada's Mackenzie Bison Sanctuary, according to media reports. Over 400 bison perished in 2012 to date, likely as a result of contracting anthrax from wallowing in dust baths, and doubled the number of bison that died in 1994 during the Canadian territory's previous large anthrax outbreak.

Australia's Great Barrier Reef from 13 August 2012 image
Australia's Great Barrier Reef
from 13 August 2012 image
Source: NASA

A research study published during August indicated that skin cancers were detected in wild fish for the first time. Coral trout sampled near the Australia's Great Barrier Reef exhibited the disease. Environmental causes such as stratospheric ozone depletion were cited as potential factors given the observed similarities with UV-induced melanomas on laboratory fish.

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Synoptic Discussion

Note: This Synoptic Discussion describes recent weather events and climate anomalies in relation to the phenomena that cause the weather. These phenomena include the jet stream, fronts and low pressure systems that bring precipitation, high pressure systems that bring dry weather, and the mechanisms which control these features — such as El Niño, La Niña, and other oceanic and atmospheric drivers (PNA, NAO, AO, and others). The report may contain more technical language than other components of the State of the Climate series.


NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.


Synoptic Discussion

Monthly upper-level circulation pattern and anomalies
Monthly upper-level circulation pattern and anomalies.

The weather patternweather pattern over North America during August 2012 consisted of a battle between subtropical high pressure (High, or upper-level ridge) to the south and the polar jet stream and associated storm track to the north. The jet stream frequently pushed upper-level troughs and cool fronts into the High over the eastern U.S., while the remnants of Hurricane Isaac moved up the Mississippi Valley at the end of the month and became absorbed into a cool front along the Ohio Valley at the beginning of September. When averaged over the month of August, this pattern resulted in warmer-than-average temperatures beneath an upper-level ridge over the western U.S. and cooler-than-average temperatures beneath an upper-level trough over the Southeast. Although summer monsoon showers brought above-normal precipitation to parts of the Southwest, descending air ("subsidence") associated with the High dominated the West and Great Plains, giving Nebraska, Washington, and Wyoming the driest August in the 1895-2012 record. Numerous wildfires broke out in the hot, dry, windy weather across the West and Plains, giving August 2012 a record high acreage burned. This weather pattern inhibited the formation of tornadoes, with the preliminary national count of 52 tornadoes being below the long-term average. Of the tornadoes that did occur, many were associated with Isaac.

The movement of fronts in the Midwest and East, and monsoon showers in the West, can be seen in the weekly above-normal precipitation anomaly patterns (weeks 1, 2, 3, 4, 5). The persistent dryness in the Northwest and much of the Plains is also evident. The weather pattern during August shielded the U.S. mainland from most tropical activity. Of the six Atlantic Basin tropical storms and hurricanes that formed during the month, only Isaac made landfall. And while significant flooding occurred with Isaac, especially along the Gulf coast (Louisiana and Mississippi had the second wettest August on record), its rains brought relief to some parts of the Midwest drought area. Beneficial rains contracted the drought area in the Southeast and rainfall from Isaac improved drought conditions in the Lower Mississippi and Ohio valleys. But drought expanded in the West and intensified in the Great Plains beneath the hot, dry ridge. According to the end-of-August (August 28) U.S. Drought Monitor, 62.9% of the contiguous U.S. (52.6% of the U.S. including Alaska, Hawaii, and Puerto Rico) was affected by moderate to exceptional drought overall. These values are about the same as the end of July. However, the areas affected by the worst drought categories (extreme and exceptional drought) increased, indicating that the drought has gotten more intense. According to the Palmer Drought Index, which goes back to the beginning of the 20th century, 55.1% of the contiguous U.S. was in moderate to extreme drought, a decrease of about 3 percent compared to last month. The percent area in severe to extreme drought increased to 39.0%, confirming that the drought has intensified. The 2012 Palmer Drought Index percent area values have been exceeded only by the droughts of the 1930s and 1950s.

The movement of the cool fronts can also be seen in the weekly temperature anomaly maps (weeks 1, 2, 3, 4, 5). The persistence of warm anomalies in the West, and frequent excursions of cool air masses into the central and eastern U.S., resulted in the warmest August in the 1895-2012 record for Nevada and cooler-than-normal monthly temperatures for six states in the Midwest and Southeast. In total, twelve states (in the West and Northeast) had the tenth warmest, or warmer, August. On a local basis, twice as many record warm highs and lows occurred than record cold highs and lows. Nearly 2000 daily high temperature records and 2300 record warm daily low temperatures were tied or broken. In comparison, about 1100 record low temperatures and 1000 record cool daily high temperatures were tied or broken. (These numbers are preliminary and are expected to increase as more data arrive.) On balance, the warm and cold anomalies contributed to a national Residential Energy Demand Temperature Index (REDTI) for August 2012 that was above average but nowhere near a record.

When averaged together, the mixture of temperature and precipitation extremes gave the U.S. the 16th warmest and 57th driest August in the 118-year record. Averaging extremes tends to cancel them out (as in the case for national precipitation this month). But when extremes are combined cumulatively, like in the U.S. Climate Extremes Index (CEI), they may tell a different story. Nationally, the large spatial extent of very dry conditions ranked fourth largest for August 2012 (behind August 1934, 1954, and 1936). However, the CEI components for percent area with very warm maximum and minimum temperatures ranked only in the top 20, and the other components ranked even lower, giving the U.S. an August CEI that ranked only 22nd largest. Regionally, the August 2012 CEI for the West and Southwest regions ranked fifth and seventh largest, respectively. The preponderance of unusual warmth and dryness for the last several months has ranked the national CEI largest for the last six months (March-August) and year-to-date (January-August), second largest for the last twelve months (September-August), and eighth largest for the summer (June-August).

Subtropical highs, and cold fronts and low pressure systems moving in the storm track flow, are influenced by the broadscale atmospheric circulation. Five such large-scale atmospheric circulation drivers were potentially influential during August:

Map of monthly temperature anomalies Map of monthly precipitation anomalies

Upper-level circulation pattern and anomalies averaged for the last three months
Upper-level circulation pattern and anomalies averaged for the last three months.

Examination of these circulation indices and their teleconnection patterns, and comparison to observed August and June-August 2012 temperature, precipitation, and circulation patterns, suggests that ENSO, PNA, and NAO had little influence on the observed weather patterns. The AO and EP-NP may have exerted some influence on the weather this past month and season. As noted above, some of the indices were near neutral values for part or much of the month. When the atmospheric circulation drivers are neutral or in a state of transition, their influence becomes difficult to trace and can be overwhelmed by other competing forces, including random fluctuations in the atmosphere.

Tornadoes

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.


August 2012 Tornadoes Year-to-date
August 2012 Year-to-Date Tornado Count

According to data from the Storm Prediction Center, during August, there were 52 preliminary tornado reports. This is less than the 1991-2010 August average of 83 tornadoes, and once the final tornado count is confirmed, the August 2012 number could be revised lower. This marks the least active August since 2003, in terms of the number of tornadoes reported, when 44 tornadoes were confirmed. The majority of the tornadoes during the month were weak and associated with Hurricane Isaac as it traversed the Florida Keys and made landfall along the Louisiana coast at the end of August. The below average tornado activity during August is similiar to the rest of 2012 to-date. The preliminary number of tornadoes during the January-August 2012 period was 785 with 76 tornado confirmations still pending for July and August, marking the lowest January-August tornado count since 2002.

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Hurricanes & Tropical Storms

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.


Note: This report catalogs recent tropical cyclones and places each basin's tropical cyclone activity in a climate-scale context. It is not updated in real time. Users seeking real time status and forecasts of tropical cyclones should visit The National Hurricane Center.

Atlantic Basin

Ernesto
Tropical Storm Ernesto Satellite Image


Ernesto Track
Tropical Storm Ernesto Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Ernesto
Cyclogenesis Date 08/03
Cyclolysis Date 08/10
Highest Saffir-Simpson Category Cat 1
Maximum 6-hr Sustained Wind 86 mph (75 kt or 139 km/h)
Min Pressure 980 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 7.7700 x 104
Landfall Information (date, location and sustained winds) 08/08 - Yucatan Peninsula, Mexico (75 kt or 139 km/h)
Deaths 7
*The (ACE) Index calculations are based on preliminary data.

Florence
Tropical Storm Florence Satellite Image


Florence Track
Tropical Storm Florence Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Florence
Cyclogenesis Date 08/04
Cyclolysis Date 08/06
Highest Saffir-Simpson Category TS
Maximum 6-hr Sustained Wind 58 mph (50 kt or 93 km/h)
Min Pressure 1009 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 1.4306 x 104
Landfall Information (date, location and sustained winds)
Deaths 0
*The (ACE) Index calculations are based on preliminary data.

Helene
Tropical Storm Helene Satellite Image


Helene Track
Tropical Storm Helene Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Helene
Cyclogenesis Date 08/18
Cyclolysis Date 08/18
Highest Saffir-Simpson Category TS
Maximum 6-hr Sustained Wind 46 mph (40 kt or 74 km/h)
Min Pressure 1004 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) .4050 x 104
Landfall Information (date, location and sustained winds)
Deaths 0
*The (ACE) Index calculations are based on preliminary data.

Gordon
Tropical Storm Gordon Satellite Image


Gordon Track
Tropical Storm Gordon Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Gordon
Cyclogenesis Date 08/16
Cyclolysis Date 08/20
Highest Saffir-Simpson Category Cat 2
Maximum 6-hr Sustained Wind 109 mph (95 kt or 176 km/h)
Min Pressure 965 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 8.3025 x 104
Landfall Information (date, location and sustained winds)
Deaths 0
*The (ACE) Index calculations are based on preliminary data.

Isaac
Tropical Storm Isaac Satellite Image


Isaac Track
Tropical Storm Isaac Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Isaac
Cyclogenesis Date 08/21
Cyclolysis Date 08/30
Highest Saffir-Simpson Category Cat 1
Maximum 6-hr Sustained Wind 81 mph (70 kt or 130 km/h)
Min Pressure 968 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 8.4350 x 104
Landfall Information (date, location and sustained winds) 08/25 - Haiti (60 kt or 111 km/h)
08/25 - Cuba (50 kt or 93 km/h)
08/28-29 - southeastern Louisiana (70 kt or 130 km/h)
Deaths 41
*The (ACE) Index calculations are based on preliminary data.

Kirk
Tropical Storm Kirk Satellite Image


Kirk Track
Tropical Storm Kirk Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Kirk
Cyclogenesis Date 08/29
Cyclolysis Date 09/02
Highest Saffir-Simpson Category Cat 2
Maximum 6-hr Sustained Wind 104 mph (90 kt or 167 km/h)
Min Pressure 970 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 7.3475 x 104
Landfall Information (date, location and sustained winds)
Deaths 0
*The (ACE) Index calculations are based on preliminary data.

Leslie
Tropical Storm Leslie Satellite Image


Leslie Track
Tropical Storm Leslie Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Leslie
Cyclogenesis Date 08/30
Cyclolysis Date 09/11
Highest Saffir-Simpson Category Cat 1
Maximum 6-hr Sustained Wind 75 mph (65 kt or 120 km/h)
Min Pressure 985 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 15.0775 x 104
Landfall Information (date, location and sustained winds)
Deaths 0
*The (ACE) Index calculations are based on preliminary data.

West North Pacific Basin

Haikui
Tropical Storm Haikui Satellite Image
Haikui Track
Tropical Storm Haikui Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Haikui
Cyclogenesis Date 08/04
Cyclolysis Date 08/09
Highest Saffir-Simpson Category Cat 1
Maximum 6-hr Sustained Wind 75 mph (65 kt or 120 km/h)
Min Pressure 965 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 5.9700 x 104
Landfall Information (date, location and sustained winds) 08/07 - China (60 kt or 111 km/h)
Deaths 19
*The (ACE) Index calculations are based on preliminary data.

Kirogi
Tropical Storm Kirogi Satellite Image
Kirogi Track
Tropical Storm Kirogi Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Kirogi
Cyclogenesis Date 08/05
Cyclolysis Date 08/10
Highest Saffir-Simpson Category TS
Maximum 6-hr Sustained Wind 52 mph (45 kt or 83 km/h)
Min Pressure 990 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 3.0325 x 104
Landfall Information (date, location and sustained winds)
Deaths 0
*The (ACE) Index calculations are based on preliminary data.

Helen
Tropical Storm Helen Satellite Image
Helen Track
Tropical Storm Helen Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Helen(Kai-tak)
Cyclogenesis Date 08/13
Cyclolysis Date 08/18
Highest Saffir-Simpson Category Cat 1
Maximum 6-hr Sustained Wind 81 mph (70 kt or 130 km/h)
Min Pressure 990 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 6.1750 x 104
Landfall Information (date, location and sustained winds) 08/14 - Isabela, Philippines (55 kt or 102 km/h)
08/17 - Guangdong, China (70 kt or 130 km/h)
08/17 - Vietnam, Loas (60 kt or 111 km/h)
Deaths 40
*The (ACE) Index calculations are based on preliminary data.

Igme
Tropical Storm Igme Satellite Image
Igme Track
Tropical Storm Igme Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Igme(Tembin)
Cyclogenesis Date 08/19
Cyclolysis Date 08/30
Highest Saffir-Simpson Category Cat 4
Maximum 6-hr Sustained Wind 132 mph (115 kt or 213 km/h)
Min Pressure 945 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 28.7050 x 104
Landfall Information (date, location and sustained winds)
Deaths 10
*The (ACE) Index calculations are based on preliminary data.

East North Pacific Basin

Gilma
Tropical Storm Gilma Satellite Image
Gilma Track
Tropical Storm Gilma Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Gilma
Cyclogenesis Date 08/07
Cyclolysis Date 08/11
Highest Saffir-Simpson Category Cat 1
Maximum 6-hr Sustained Wind 81 mph (70 kt or 130 km/h)
Min Pressure 984 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 4.8675 x 104
Landfall Information (date, location and sustained winds)
Deaths
*The (ACE) Index calculations are based on preliminary data.

Hector
Tropical Storm Hector Satellite Image
Hector Track
Tropical Storm Hector Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Hector
Cyclogenesis Date 08/12
Cyclolysis Date 08/15
Highest Saffir-Simpson Category TS
Maximum 6-hr Sustained Wind 52 mph (45 kt or 83 km/h)
Min Pressure 993 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 2.3025 x 104
Landfall Information (date, location and sustained winds)
Deaths
*The (ACE) Index calculations are based on preliminary data.

Ileana
Tropical Storm Ileana Satellite Image
Ileana Track
Tropical Storm Ileana Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Ileana
Cyclogenesis Date 08/28
Cyclolysis Date 09/02
Highest Saffir-Simpson Category Cat 1
Maximum 6-hr Sustained Wind 86 mph (75 kt or 139 km/h)
Min Pressure 987 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 6.5900 x 104
Landfall Information (date, location and sustained winds)
Deaths
*The (ACE) Index calculations are based on preliminary data.

Drought

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.

Issued 17 September 2012
Contents Of This Report:
Map showing Palmer Z Index

National Drought Overview

[top]


Detailed Drought Discussion

Overview

August 2012 was another warmer-than-average month (16thwarmest August on record, based on data back to 1895), with precipitation near average (57th driest August), when weather conditions are averaged across the country. Cool fronts swept across the Midwest and East (weeks 1, 2, 3, 4, 5) while a strong high pressure system (High, or upper-level ridge) kept its stranglehold over much of the West, resulting in a monthly pattern of anomalous warmth in the West and Northeast and below-normal temperatures in the Midwest and Southeast. Descending air ("subsidence") associated with the High inhibited precipitation in the Northwest to Central Plains states, while passing fronts and the remains of Hurricane Isaac triggered areas of rain in the East and South and monsoon showers brought rain to the Southwest (weeks 1, 2, 3, 4, 5). The dry weather, in combination with increased evaporation caused by the record heat, expanded drought conditions in the West and intensified drought conditions in the Plains. Nationally, the moderate-to-exceptional (D1-D4) drought footprint remained about the same at 53 percent of the country, compared to last month, while the percentage in the abnormally dry to exceptional drought category increased to about 78 percent. About 19 percent of the country was in the worst drought categories (D3-D4, extreme to exceptional drought), fractionally higher than last month. The Palmer Drought Index, whose data base goes back 113 years, is relied upon for drought comparisons before 2000. The August 2012 Palmer value of 55 percent in moderate to extreme drought is a decrease of about 3 percent compared to last month, but the percent area in severe to extreme drought increased to about 39 percent, confirming that the drought has intensified.

The U.S. Drought Monitor drought map valid August 28, 2012
The U.S. Drought Monitor drought map valid August 28, 2012.

By the end of the month, the core drought areas in the U.S. included:

Isaac: The remnants of Hurricane Isaac brought beneficial rain to the Lower to Mid Mississippi Valley drought areas during the waning days of August (August 30th and 31st). Isaac's rain moved into the Ohio Valley and became absorbed into a cool front during the first few days of September (September 1st, 2nd, 3rd), improving drought conditions across parts of the Midwest (USDM for September 4th vs. August 28th). While Isaac's rains reduced the percent area of the Midwest in extreme to exceptional drought from 33 percent in late August to 14 percent in early September, thus reducing the severity of drought here, the rains were not enough to erase months of deficits, with the percent area in moderate to exceptional drought remaining fairly constant (reduced from 65 percent to 63 percent), and the Midwest improvement does not show up in the end-of-August monthly drought indicators (such as the Palmer Drought Index, streamflow, etc.). Isaac had little effect on the national drought picture, with roughly the same percent area of the U.S. in the various USDM drought categories before as after. This is due to drought worsening and expanding in the Plains and West to counterbalance the improvement in the Midwest.


Palmer Drought Index

The Palmer drought indices measure the balance between moisture demand (evapotranspiration driven by temperature) and moisture supply (precipitation). The Palmer Z Index depicts moisture conditions for the current month, while the Palmer Hydrological Drought Index (PHDI) and Palmer Drought Severity Index (PDSI) depict the current month's cumulative moisture conditions integrated over the last several months.

Palmer Z Index map Palmer Hydrological Drought Index map

By August 31st, rain from frontal passages had improved short-term drought conditions (as seen on the Palmer Z Index map) in parts of the Midwest and Southeast, decreasing the intensity of long-term drought conditions there (PDSI from end of August compared to end of July). Rains from Isaac had cut into the drought area in Arkansas, but continued hot and dry weather intensified drought conditions (both short-term [Z Index] and long-term [PHDI] conditions) across much of the Plains and West. August dryness (Palmer Z Index map) reduced the long-term wet conditions (PDSI from end of August compared to end of July) in the Pacific Northwest. The August 2012 PHDI map also reflects the long-term nature of the drought conditions. The Z Index and PHDI maps in combination show that precipitation brought relief to parts of the Southeast and Midwest drought areas, and reduced precipitation shrank long-term wet areas in the Northwest, but for much of the rest of the country — drier-than-normal weather persisted over the existing drought areas.


Palmer Drought Model Potential Evapotranspiration

August 2012 Precipitation minus Potential Evapotranspiration map
Precipitation minus Potential Evapotranspiration for August 2012 calculated using the Palmer Model.
Summer (June-August) 2012 Precipitation minus Potential Evapotranspiration ma
Precipitation minus Potential Evapotranspiration for Summer (June-August) 2012 calculated using the Palmer Model.

During August 2012, temperatures were much above normal across the western and northeastern U.S., but cooler from the Great Plains to the Midwest and Southeast. This helped reduce the amount of potential evapotranspiration (PE, or natural water demand) in the eastern parts of the Primary Corn and Soybean agricultural belt. But the amount of precipitation (P, or water supply) that fell was still not sufficient to meet the PE demand in most parts of the country, so the net difference — water supply minus water demand (August P minus PE) — was still negative across much of the nation. This continued to sap soil moisture reserves, stress crops and other vegetation, and shrink streams. Even if normal precipitation amounts had occurred, it would not have been enough to meet PE demand in most areas.

The hardest-hit areas (as measured by pasture and soil moisture impacts) were the Rocky Mountain states, Central Plains, and Ohio Valley. The West normally has an arid climate. But even taking that into consideration, these areas have had anomalously warm and dry weather conditions persistently for the summer (June-August temperature, precipitation), growing season (April-August precipitation), and year-to-date (January-August temperature, precipitation). This has had a cumulative impact on water supply versus water demand throughout this period, with widespread persistently negative P minus PE (June-August, April-August, January-August). If normal precipitation had fallen during this time, P minus PE values would still have been negative for the summer (June-August) and growing season (April-August) for these agricultural areas, but the stress on crops would have been far less, and the year-to-date (January-August) P minus PE values would have been positive in the eastern Corn and Soybean belt.


Standardized Precipitation Index

The Standardized Precipitation Index (SPI) measures moisture supply. The SPI maps here show the spatial extent of anomalously wet and dry areas at time scales ranging from 1 month to 24 months.

1-month Standardized Precipitation Index 2-month Standardized Precipitation Index 3-month Standardized Precipitation Index

The 1-month SPI shows the main area of dryness from the Pacific Northwest to the Central Plains, with other areas dry in the Upper Midwest, Southern Plains to Southern Rockies, and mid-Appalachian Mountains. The Northwest and Northern Rockies are dry at 2 months, but wet conditions dominate there at 3 to 9 months. The summer monsoon in the Southwest is evident from 1 to 3 months, with neutral to dry conditions dominating at 9 to 24 months. Dryness is widespread from the Central Rockies, across the Plains, to the Midwest from 2 to 12 months, especially at 3 to 6 months. The Southeast and parts of the Midwest are wet at 1 to 2 months, but the Southeast wetness becomes limited to the Gulf and Atlantic coasts from 3 to 12 months, with a dry core becoming evident around Georgia at 6 months and stretching to 24 months. Dryness dominates in the Southern Plains at 24 months, while the northern tier states are wet. Wetness extends from New England to the Southern Appalachians at 12 and 24 months.


6-month Standardized Precipitation Index 12-month Standardized Precipitation Index 24-month Standardized Precipitation Index


Agricultural and Hydrological Indices and Impacts

USDA topsoil moisture short to very short
USDA topsoil moisture short to very short
USGS monthly streamflow percentiles
USGS monthly streamflow percentiles

Drought conditions were reflected in numerous agricultural, hydrological, and other meteorological indicators, both observed and modeled.

Agricultural:

Percent of Crops in Poor to Very Poor Condition
Crop 7/29 8/26 9/2 9/9
Corn 48% 52% 52% 52%
Soybeans 37% 38% 37% 36%
Sorghum 42% 50% 50% 50%
Cotton 22% 28% 28% 30%
Pastures and
Rangeland
57% 59% 59% 58%

Based on end-of-August (August 26th) U.S. Department of Agriculture reports, 52 percent of the nation's corn crop was rated in poor to very poor condition. This is slightly more than the 48 percent at the end of July. Thirty-eight percent of the national soybean crop was rated poor to very poor (compared to 37 percent a month ago), 50 percent of sorghum (42 percent last month), and 59 percent of the nation's pasture and rangeland (57 percent last month). In some states, nearly all of the pasture and rangeland was rated poor to very poor (Missouri at 99 percent, Nebraska 95 percent, Kansas 92 percent, Illinois 90 percent). In the waning days of the growing season, crop condition changed little during the first two weeks of September, although pastures and rangeland improved in some areas from the rains of Isaac (as of September 9th, Missouri had 92 percent in poor to very poor condition while Illinois dropped to 62 percent and Arkansas to 68 percent [from 84 percent]). But on a national scale, little improvement occurred with 83 percent of corn, 80 percent of soybeans, and 72 percent of cattle still in drought (as of September 4th). The drought has taken a toll on the nation's soil moisture, with virtually all of the topsoil in the Rocky Mountain to Central Plains states short or very short of moisture. The rainfall from Isaac improved soil moisture conditions in Arkansas, Missouri, Illinois, and Indiana during the first week of September.

Map showing USDA pasture and rangeland conditions
Map showing USDA pasture and rangeland conditions.

Hydrological:

USGS groundwater percentile map
USGS groundwater percentile map.

Meteorological:

Map showing number of days with precipitation
Map showing number of days with precipitation.


Regional Discussion

August 2012 was characterized by below-normal rainfall across most of the Hawaiian Island stations. Moderate to extreme drought affected 54 percent of the state, about the same as last month. Longer-term conditions continued drier than normal (last 2, 3, 6, 12, 24, and 36 months, year-to-date, and water-year-to-date), especially for the southern islands.

In Alaska, August 2012 was generally drier than normal in the eastern and southern regions and wetter than normal in the west and north. Many central to southeast stations were drier than normal at the 2-month time scale, and dryness extended from central Alaska to the north coast at 6 to 8 months, but otherwise a mixed pattern prevailed (3, 12, 24, and 36 months, and water-year-to-date). An area of abnormal dryness covered the northern areas on the USDM map.

Puerto Rico was drier than normal in a band from the west coast to the central regions, and along much of the east coast, during August and for the last 2 to 3 months. Southern and eastern portions of Puerto Rico have been persistently drier than normal at longer time scales (6 months, year to date, and water year to date). The August 28th USDM map had an area of abnormally dryness in the south central to eastern areas to reflect these rainfall deficits.

Current month state precipitation ranks 3-month state precipitation ranks

Nebraska statewide precipitation, May-August, 1895-2012
Nebraska statewide precipitation, May-August, 1895-2012.

Over a fifth of the U.S. was very dry (the driest ten percent of the historical record) during August 2012. The dryness was partially balanced out by a significant area (9 percent) that was very wet, resulting in a national rank for August 2012 of 57th driest August in the 118-year record. On a statewide basis, August 2012 ranked in the top ten driest Augusts for six states — from the Northwest to the Central Plains — and ranked as the driest August for Nebraska, Washington, and Wyoming. Nine other states ranked in the driest third of the historical record. The spatial pattern of dryness at the three month time scale stretched from the Rocky Mountain states to the Ohio Valley and parts of the Northeast. Again, Nebraska and Wyoming had the driest June-August on record. Six other states had the tenth driest, or drier June-August and 16 other states ranked in the driest third of the historical record.

6-month state precipitation ranks 12-month state precipitation ranks

Wyoming statewide precipitation, March-August, 1895-2012
Wyoming statewide precipitation, March-August, 1895-2012.

The spatial pattern at the six month time scale is similar to the spatial pattern of summer (June-August). Delaware and Wyoming had the driest March-August on record, eight other states ranked in the top ten category, and an additional 13 states were in the driest third of the historical record. A similar pattern was evident for the year-to-date. At the 12-month time scale, dryness dominates from the West to the Midwest. September 2011-August 2012 ranked in the top ten driest category for six states, with 13 other states ranking in the driest third of the historical record. Delaware, Nebraska, and Wyoming each ranked second driest for September 2011-August 2012.

3-month state temperature ranks 3-month state precipitation ranks

Wyoming statewide average Palmer Z Index, June-August, 1895-2012
Wyoming statewide average Palmer Z Index, June-August, 1895-2012.

August 2012 had near to below-normal temperatures for the Midwest to Southeast, interrupting a warm streak for that part of the country, but record to near-record heat occurred for states in the West. For most of the last twelve months, the extreme dryness has been accompanied by extreme heat for the drought areas across the country. For example, both Colorado and Wyoming had the hottest summer on record and Nebraska and Wyoming had the driest summer on record. As noted earlier, excessive heat increases evapotranspiration and exacerbates drought. The combination of driest and third warmest summer gave Nebraska the second most severe June-August averaged Palmer Z Index in the 1895-2012 record, behind 1936. The driest and warmest summer gave Wyoming the most severe June-August averaged Palmer Z Index on record. The dryness and excessive heat have been so persistent for the state that Wyoming has had the most severe averaged Palmer Z Index for the last six months (March-August) and the third most severe averaged Palmer Z Index for the last twelve months (September-August) (behind 1934 and 2002).

Primary Corn and Soybean Belt Palmer Z Index, January 2012-August 2012 Percent area of the Primary Corn and Soybean Belt in moderate to extreme drought, January 1900-August 2012

Primary Corn and Soybean Belt temperature, March-August, 1895-2012
Primary Corn and Soybean Belt temperature, March-August, 1895-2012.

Corn and Soybean Belt

The Primary Corn and Soybean agricultural belt has been especially hard hit by drought this year. Each month of the growing season has had significant short-term dryness (as measured by the Palmer Z Index). This region, collectively, has experienced the warmest and seventh driest March-August in 2012, resulting in the fourth most severe Palmer Z Index (behind 1936, 1934, and 1988). The extreme severity of the dryness and evapotranspiration demand over the growing season resulted in a rapid increase in the percent area of this agricultural belt experiencing moderate to extreme drought (as defined by the Palmer Drought Index) and moderate to exceptional drought (for the Midwest and High Plains as defined by the USDM). The August rains in the eastern part of this region were beneficial and helped reduce the intensity of the drought there, but they did little to shrink the overall drought area for the entire region. By the end of August 2012, about 83 percent of the Primary Corn and Soybean Belt was experiencing moderate to extreme drought (based on the Palmer Drought Index), surpassing all previous droughts except those in 1988 and the 1930s.


Western U.S.


Percent area of the Western U.S. in moderate to extreme drought, based on the Palmer Drought Index
Percent area of the Western U.S. in moderate to extreme drought, based on the Palmer Drought Index.

Showers and thunderstorms from the summer monsoon brought above-normal rainfall to parts of the Southwest again this month, but most of the West was dry, especially from the Pacific Northwest to Northern Rockies where Washington and Wyoming had the driest August on record. The combination of dryness and excessive heat resulted in a large area of extreme short-term drought. The rain that fell in the extreme Southwest did little to change the overall percent area in drought. Drier-than-normal weather has dominated much of the West for the water year to date (October-present), as reflected in low elevation as well as high elevation (SNOTEL) precipitation, especially for the southern half of the West. Reservoir storage was below average, statewide, in most of the western states. Hot, dry, windy weather contributed to many wildfires across the West. According to the USDM, 74 percent of the West was experiencing moderate to exceptional drought at the end of August, a 6 percent increase compared to July. The Palmer Drought Index percent area statistic was about 55 percent, about the same as last month.

National Palmer Z Index, January 2010-August 2012 Percent area of the U.S. in moderate to extreme drought, January 1900-August 2012


Historical Analogs

The persistent warmth and dryness of the last couple years continued on a national scale during August 2012. Water demand has consistently outstripped water supply on a national scale for the last 15 consecutive months, as indicated by the persistently negative nationally-integrated Palmer Z Index. This is largely behind the rapid expansion of drought this year (USDM, Palmer Drought Index). While dropping slightly from the July peak, the percent area in moderate drought or worse remained quite high, well above the 50 percent level. The last time drought was as extensive as summer 2012 was in December 1956 when about 58 percent was in moderate to extreme drought.

Even though every drought is different, historical analogs to the current drought can be determined by comparing the spatial pattern and intensity of various climate indicators using statistical tools such as the correlation coefficient and mean absolute difference. The table below lists those years that have the closest relative spatial pattern to that for August, summer (June-August), and year-to-date (January-August) 2012 for four climate indicators (precipitation, temperature, PHDI, and Palmer Z Index). For August, many analogs can be found from many different years. There is no consistent pattern between the indicators except for PHDI, which most closely matches the 1950s. When each month from January-August 2012 is compared individually to its corresponding month from previous years, the best matches for precipitation, PHDI, and Palmer Z Index come from drought years, with 1988 standing out. When average year-to-date 2012 conditions are compared to average year-to-date of past years, 1955 stands out for PHDI and the Palmer Z Index. For the summer months individually, the 1930s and 1950s are prominent for the drought indicators (PHDI and Palmer Z Index). For average summer conditions, 1988 stands out for precipitation and the Palmer Z Index, the 1950s for PHDI, and 2002 and 2006 for temperature.

Analog Years to 2012 based on Five Climate Criteria (The top two analog years are listed for January-August and June-August)
Month or Season Precipitation Temperature PHDI Palmer Z Index
August 2012 (all months) July 1920 July 1979 May 1954 September 1943
August 2012 (only August's) August 1919 August 1985 August 1955 August 1970
January-August 2012 (each month individually) 1934, 1988 1921, 1946 1955, 2006 1988, 2002
June-August 2012 (each month individually) 1985, 1913 1901, 2002 1955, 1954 1934, 1931
Year-to-date (Jan-Aug) 2012 1966, 1926 2006, 1921 1955, 2000 1988, 1955
Summer (Jun-Aug) 2012 1988, 1946 2002, 2006 1955, 1954 1934, 1988

A more detailed drought discussion, provided by the NOAA Regional Climate Centers and others, can be found below.

SoutheastSouthMidwestNortheastHigh Plains
WestUpper Colorado River BasinPacific Islands

As noted by the Southeast Regional Climate Center, August mean temperatures were near normal to below normal and precipitation was generally above normal across the Southeast. Monthly temperatures were variable across Puerto Rico and below normal over the U.S. Virgin Islands. Heavy rainfall from Isaac fell on parts of the Southeast, including Puerto Rico where 4 to 8 inches fell with locally heavier amounts across the interior mountains. For the second straight month, drought conditions improved or stabilized across the Southeast. By the end of August, over 60 percent of the region was drought-free, up from 40 percent at the end of July. Most notably, drought conditions were eliminated in Florida (the first time the state has been drought-free in over two years), and across a large section of Alabama. Additionally, improvements of one to two drought categories in the USDM were observed across South Carolina by the end of the month. There was a slight contraction of drought conditions across central Georgia; however, over one-third of the state remained in extreme (D3) or exceptional (D4) drought. By the end of the month, the harvesting of row crops was nearly complete (some delays were reported in areas that were particularly wet, especially along the Florida Panhandle) and most crops were reported to be in generally good condition across much of the region. The beneficial rain also helped livestock and pasture conditions, though some farmers were beginning to spray for disease and insects. Tobacco and cotton were also being sprayed in areas that were particularly wet.

As explained by the Southern Regional Climate Center, August precipitation varied dramatically over the Southern region, mostly in part to Hurricane Isaac which drenched much of Louisiana, Mississippi, and southern Arkansas. Elsewhere, such as Texas and Oklahoma, conditions were quite dry. The driest part of the region was observed in southern Texas, where a majority of the stations received only between 0 to 50 percent of normal precipitation. Temperatures varied spatially across the region, with cooler-than-normal values in the east and warmer-than-normal values in the west. Drought conditions remain relatively unchanged, despite heavy rainfall totals in the southeastern portion of the region. This is in part due to the fact that much of the drought in this region is situated in areas outside of the reach of Hurricane Isaac. Conditions deteriorated though most of Oklahoma, with almost the entire state being in extreme or exceptional drought. Elsewhere, the majority of Texas was still experiencing moderate to severe drought conditions. This was also the case in western Tennessee, where conditions were generally drier than normal for the month. In the case of Arkansas, much of the northern portions of the state were in exceptional to extreme drought conditions.

As summarized by the Midwest Regional Climate Center, August temperatures averaged to near normal across the Midwest. The first and last weeks of the month were above normal but the middle two weeks were below normal. Daily records followed the same pattern with mostly record highs on the first and last eight days of the month while mostly record lows were recorded from the 9th to the 23rd. The two cooler weeks in the middle of the month were a welcome break in a warm year. Precipitation totals were above normal in south central Missouri and from western Kentucky, into southeast Illinois, across northern and central Indiana, and into northwest Ohio and southeast Michigan. The rest of the region was below normal with northern and central Missouri hardest hit at less than 25 percent of normal for August. Summer rainfall was below normal for most of the region. Summer totals were less than half of normal in parts of Missouri, Iowa, Illinois, southern Indiana, southwest Wisconsin, and southwest Minnesota. A few locations in the upper Midwest and Kentucky were slightly above normal for the summer. Year-to-date precipitation totals were less than 75 percent of normal for most of Missouri, Iowa, Illinois, Indiana, and western Kentucky. The upper Midwest had a mix of above and below normal totals for the year-to-date. The rainfall deficits for those areas ranged from 6 to 14 inches (150 to 350 mm).

Drought conditions in the Midwest saw both improvement and degradation during August. In southern Michigan, northern Indiana, and northwest Ohio, rains eased the drought but in Missouri and western Iowa conditions got worse through the month. While the percentage of the region in drought dropped from 71 percent to 65 percent in August, the areas in extreme (32 to 33 percent) and exceptional (5 to 7 percent) drought increased. The biggest improvements were in Indiana, Michigan, and Ohio while Iowa and Missouri had the largest degradations. August rains were too late for improvements in the corn crop conditions but there were some improvements in soybean conditions in locations that received above normal rains.

As noted by the Northeast Regional Climate Center, August temperatures averaged 1.7 degrees F (0.9 degrees C) above normal in the Northeast region and it was the twelfth warmest summer in the region since recordkeeping began in 1895. August precipitation averaged 3.90 inches (99.1 mm) regionwide, which was 100 percent of normal. For the most part, areas closest to the coast saw above normal rainfall, while inland regions were drier than normal. Maine (127 percent), Maryland (123 percent), Massachusetts (124 percent), New Hampshire (122 percent) and New Jersey (134 percent) were the states with positive precipitation departures. Departures in the remaining states ranged from 70 percent of normal in Vermont to 100 percent in Delaware. This was the first month since September 2011 that Delaware's precipitation was not below normal. Summer (June through August) precipitation totals averaged below normal in the Northeast (95 percent) and in eight of the twelve states. The four wetter-than-normal states were New Hampshire (102 percent), Rhode Island (106 percent), New Jersey (108 percent), and Maine (126 percent). It was the eleventh wettest summer since 1895 in Maine. Departures in the drier-than-normal states ranged from 98 percent in Massachusetts to 77 percent in West Virginia, where it was the 22nd driest summer in 118 years. The USDM issued August 28, 2012 indicated that conditions improved slightly in Delaware, but the southern two-thirds of the state were still in D1 (moderate) or D2 (severe) drought. In addition, slight improvements were seen in Maryland where most areas of D2 drought surrounding Chesapeake Bay on July 31 improved to D1 on August 28. Conditions in Massachusetts also improved — the region of D1 drought in the western two thirds at end of July shrank to just the southwestern portions of the state. A new area of abnormally dry conditions popped up in northern Vermont.

As explained by the High Plains Regional Climate Center, for the first time since February of this year, there were widespread below-normal monthly temperatures in the High Plains region. Much of North Dakota, South Dakota, Kansas, and southern Nebraska had average temperatures which were up to 3.0 degrees F (1.7 degrees C) below normal. Meanwhile, areas of Colorado, Wyoming, southern South Dakota, and western and central Nebraska had temperatures which were above normal. August was yet another dry month for the majority of the region. A large expanse — including Wyoming, eastern Colorado, the eastern and western sides of Kansas, most of Nebraska, central and southern South Dakota, and pockets of North Dakota — had precipitation totals which were at the most 50 percent of normal. There were even areas of Wyoming, northeast Colorado, and the panhandle of Nebraska which received less than 5 percent of normal precipitation. Because of the lack of precipitation, new records were set again this month. For instance, Scottsbluff, Nebraska received no measurable precipitation and set a new record for driest August. The old record of 0.04 inch (1 mm) was set in 2001 (period of record 1893-2012). On average, Scottsbluff receives 1.30 inches (33 mm) of precipitation in August. Another location which had its driest August on record was Colorado Springs, Colorado which received only 0.12 inch (3 mm) of precipitation. This beat out the old record of 0.15 inch (4 mm) set in 1962 (period of record 1894-2012). The only areas of the region which received much needed rainfall were pockets of central North Dakota, central and northeastern Kansas, far southeastern Nebraska, and a few pockets of western Colorado. These areas had precipitation totals ranging from 110 percent of normal to 300 percent of normal.

The heavy rainfall improved drought conditions; however, at this point many of the crops will not benefit from the precipitation. According to the USDM, drought conditions worsened yet again this month across the High Plains region. By the end of August, about 88 percent of the region was under moderate (D1) to exceptional (D4) drought, with nearly 15 percent of the region in the D4 designation. In contrast, at the end of last month, only 4 percent of the region was in D4. Over the past month, the D4 areas that expanded include an area in central Nebraska that grew westward across the state and even into northeastern Colorado, an area in western Kansas that expanded all the way across the middle of the state to the eastern border, and an area in eastern Colorado that grew to include most of the southeastern corner of the state. By the end of the month over half the state of Kansas was in D4 drought. Extreme drought conditions (D3) also expanded in Colorado, Nebraska, South Dakota, and Wyoming. In addition, there was only a little over one percent of the region that did not have any sort of drought or abnormally dry conditions (D0). August was a busy month for producers as drought-damaged crops had to be chopped for silage or baled for hay in Nebraska, Kansas, and the Dakotas. The lack of feed and water caused the culling of herds to continue in Nebraska and Kansas. According to the USDA, by the end of the month 85 percent of all corn, 82 percent of all soybeans, 63 percent of all hay acreage, and 72 percent of all cattle were within an area experiencing drought conditions in the United States. This was a slight improvement from last month.

Summer (June, July, and August) 2012 went down as one of the hottest on record for many locations in the region. It was an overall dry summer for the region and most locations ranked in the top 20 driest summers. Some locations set new precipitation records as well. Grand Island, Nebraska had its driest summer on record with only 2.37 inches (60 mm) of precipitation. This was 8.45 inches (215 mm) below normal and only 22 percent of normal precipitation. The old record of 2.87 inches (73 mm) was set back in the summer of 1940 (period of record 1895-2012). The impacts from the hot and dry summer have been numerous and many more will be realized as the summer is assessed. Just some of the impacts include widespread drought, crop damage and failure, low river levels, and fish kills.

As summarized by the Western Regional Climate Center, an active monsoon doused the southern Great Basin this month, while drier conditions dominated the Northwest. Hot, dry, and windy conditions primed the region for development of numerous large and destructive wildfires. In conjunction with the fires, poor air quality prevailed in many areas, notably Idaho, Montana, and the northwestern Great Basin. Average August temperatures ranged from 2-6 F (1-3 C) above normal over most of the West, with some locations recording their hottest August on record. Only the coastal regions of northern California and southern Oregon and a few other isolated locations averaged cooler than normal for the month. Triple digit temperatures and record high minimum temperatures dominated much of the Southwest this August.

A persistent upper-level ridge and strong surface heating over the Great Basin and desert Southwest facilitated moisture transport into the area, supporting monsoon activity. The southern Great Basin saw most of the action, with numerous accounts of flash flooding, and several instances of record daily precipitation. Many locations in the Southwest that receive a large portion of their annual precipitation during the summer monsoon (Las Vegas, Nevada and Phoenix, Yuma, and Tucson, Arizona) recorded above or near average August precipitation totals and are on track to meet the monsoon season (June-Sept) average at their respective locations. In contrast, New Mexico was dry in August, and statewide has experienced its driest 18 consecutive month period on record. By mid-August, 89 percent of the pasture and rangelands there were rated as poor, one of the highest percentages in the nation. Farther north, Reno Nevada experienced the third driest water year to date in its 75-year airport record. The Pacific Northwest, which typically experiences low rainfall totals in August, was exceptionally dry this month. August 31st marked 42 days without measurable precipitation in Portland, Oregon, the 14th longest streak of this type on record. Billings, Montana experienced its driest first 8 months of the year since records began in 1934, receiving only 5.08 in (129 mm) in that time, 52 percent of average and below the previous minimum of 5.82 in (147.8 mm) in 1946.

Upper Colorado River Basin: As reported by the Colorado Climate Center, the September 4th NIDIS (National Integrated Drought Information System) assessment for the Upper Colorado River Basin (UCRB) indicated that, for the month of August, precipitation was concentrated around the central mountains of Colorado and in southeast Utah in the UCRB. The central Colorado mountains received near normal precipitation for the month, while southeast Utah received between 90 percent to almost 200 percent of average precipitation. The northern part of the UCRB was drier, with most areas receiving less than 90 percent of average precipitation. East of the basin, the Front Range and eastern Colorado were drier, receiving between 30 percent and 70 percent of average with many areas in northeast Colorado seeing zero percent of their average monthly precipitation. Water-year-to-date (WYTD) SNOTEL precipitation percentiles were low for the Yampa and Gunnison basins in Colorado, and the Wasatch range in Utah, with many sites reporting in the lowest 10th percentile or below. The northern mountains of Colorado were also dry, with most sites reporting precipitation percentiles in the teens and single digits. SNOTEL percentiles in the Upper Green basin in Wyoming were around the 20th to 30th percentiles, and percentiles in the San Juan basin were in the teens and 20s. For the month of August, temperatures were above average for all the of UCRB and eastern Colorado, with anomalies ranging from 1 to 5 degrees above normal.

Satellite vegetation conditions showed the driest vegetation over northeast Utah, with dry conditions extending into western Colorado and southern Wyoming. Very dry vegetation was also showing up over northeast Colorado and along the Arkansas valley in southeast Colorado. Reference ET (evapotranspiration) rates were still higher than average across the basin though not above the record. East of the basin, most of the reference ET sites were recording record high years, with daily ET rates between .20 to .30 inches.

About 47 percent of the USGS streamgages in the UCRB recorded normal (25th - 75th percentile) or above normal 7-day average streamflows. About 5 percent of the gages in the UCRB were recording above normal flows, while about 26 percent percent of the gages in the basin were recording much below normal or low (i.e. lowest on record) streamflows. The Yampa-White Basin was still recording in the moderate hydrologic drought category (below the 10th percentile), and the Upper San Juan River, the lower Green River and the Colorado Headwaters were mainly in the below normal category for streamflow. In August, all of the major reservoirs in the UCRB saw storage volume decreases, which is expected during the demand season. Most of the reservoirs experienced larger decreases than what is normal for this time of year with McPhee seeing a 12.3 percent decrease and Green Mountain seeing a 10.4 percent decrease. Flaming Gorge saw the smallest decrease, with storage volumes falling only 1 percent, which is average for that reservoir this time of year. All of the reservoirs were below their September averages, with most between 70 percent and 90 percent of average. Green Mountain was at 64 percent of average, Blue Mesa at 60 percent of average, and Lake Powell at 71 percent of average.

Pacific Islands: According to reports from National Weather Service offices, the Pacific ENSO Applications Climate Center (PEAC), and partners, conditions varied across the Pacific Islands.

As noted by the National Weather Service office in Honolulu, persistent and stable trade wind conditions kept most of the leeward areas of Hawaii very dry throughout August. The sustained dryness on the island of Lanai resulted in a downgrade from severe drought, or the D2 category on the USDM map, to extreme drought, or the D3 category, over the leeward slopes of the island. Severe drought on Kauai has also spread westward along the lower leeward elevations and now covers the island from Kealia to Koloa, then westward to Waimea. Elsewhere in the state, the area of extreme drought remained unchanged over leeward areas of Molokai, Maui and the Big Island. In Maui County these areas included western Molokai and southwest Maui from Kihei to Makena. Big Island extreme drought covers most of the south Kohala district, the Pohakuloa region of the Hamakua district and the north-facing slopes of Hualalai in the north Kona district. Severe drought continued over the lower elevations of southwest Kau and portions of the Humuula Saddle on the Big Island, the lower leeward slopes of the west Maui mountains and the leeward slopes of Haleakala from Kula to Kaupo. The area of moderate drought, or D1 conditions, remained unchanged in leeward Oahu.

Some drought impacts impacts in Hawaii include the following:


KAUAI.
THE AREA OF DROUGHT IMPACTS HAS BEEN SPREADING WESTWARD.   RECENT
REPORTS INDICATED POOR PASTURE CONDITIONS IN THE AREA FROM KALAHEO
TO HANAPEPE.  OTHER AREAS WITH POOR PASTURE CONDITIONS INCLUDE THE
REGION FROM KOLOA TO MAHAULEPU...AND FROM KEALIA TO KALEPA.

OAHU.
NO SIGNIFICANT CHANGES SINCE THE AUGUST 9 UPDATE.  LEEWARD PASTURES
REMAIN IN POOR CONDITION AND THE GENERAL LANDSCAPE IS VISIBLY VERY
DRY.  REPORTS FROM EARLIER IN THE SUMMER INDICATED THAT SOME
RANCHERS DESTOCKED PASTURES IN THE WAIALUA...MAKAKILO AND PALEHUA
AREAS OF THE ISLAND.

THE WATER SUPPLY IN THE WAIMANALO RESERVOIR REMAINS ABOVE
PRE-DROUGHT LEVELS.  A VOLUNTARY 10 PERCENT REDUCTION IN WATER USE
REMAINS IN PLACE AS A PRECAUTION FOR THE DRY SEASON.

MOLOKAI.
NO SIGNIFICANT CHANGES SINCE THE AUGUST 9 UPDATE.   PASTURES AND
GENERAL VEGETATION CONDITIONS REMAIN VERY POOR WEST OF KAUNAKAKAI.
AN EARLIER REPORT INDICATED THAT THE DRY CONDITIONS HAVE RESULTED IN
AN INCREASE IN AXIS DEER ENCROACHMENTS AND CROP DAMAGE AS THEY SEEK
FOOD AND WATER.

THE WATER LEVEL IN THE KUALAPUU RESERVOIR REMAINS VERY LOW.
THUS...THE STATE OF HAWAII DEPARTMENT OF AGRICULTURE HAS CONTINUED A
MANDATORY 30 PERCENT REDUCTION IN IRRIGATION WATER CONSUMPTION.

LANAI.
A REPORT FROM THE ISLAND INDICATED THAT EVEN DROUGHT-RESISTANT
PLANTS AND TREES SUCH AS KIAWE WERE STRUGGLING UNDER THE DRY
CONDITIONS.  MOUFLON SHEEP...AXIS DEER AND GAME BIRD POPULATIONS
HAVE BEEN REDUCED.  THE GREATEST IMPACTS HAVE BEEN ALONG THE LOWER
AND MIDDLE ELEVATIONS ON THE LEEWARD SIDE OF THE ISLAND AND ARE AS
BAD AS BACK IN 2010.

MAUI.
UPCOUNTRY AGRICULTURE CONTINUES TO BE SIGNIFICANTLY IMPACTED BY THE
ONGOING DROUGHT. MEDIA REPORTS INDICATED THAT RANCHERS HAVE HAD TO
INCREASE IRRIGATION...SUPPLEMENT FEED AND REDUCE HERD SIZES.
ENCROACHING AXIS DEER HAVE ALSO DECREASED FORAGE FOR LIVESTOCK.
BRUSH FIRE RISK...ESPECIALLY ALONG THE SOUTHWEST SLOPES OF
HALEAKALA...IS EXTREMELY HIGH.  THE MAUI COUNTY DEPARTMENT OF WATER
SUPPLY HAS CONTINUED THE ONGOING CALL FOR A 5 PERCENT REDUCTION IN
WATER USE FOR UPCOUNTRY RESIDENTS.  THE REQUEST FOR A 10 PERCENT
REDUCTION IN WATER USE BY CENTRAL AND SOUTH MAUI ALSO REMAINS IN
EFFECT.

BIG ISLAND.
LEEWARD KOHALA COASTAL PASTURES HAVE BEEN WITHOUT FORAGE FOR SEVERAL
MONTHS.  RANCHERS NEAR SOUTH POINT HAVE ALSO REPORTED VERY POOR
FORAGE CONDITIONS UP TO ABOUT THE 500 FT ELEVATION LEVEL.  REQUESTS
FOR FEED ASSISTANCE HAVE BEEN COMING IN FROM THE PUUKAPU...SOUTH
KOHALA...NAALEHU AND PAHALA AREAS.  A PROTEA FARMER IN THE OCEAN
VIEW ESTATES AREA REPORTED HAVING TO HAUL 20000 GALLONS OF WATER FOR
OPERATIONS. 

SPI values for seven time periods for Hawaiian Island stations, computed by the Honolulu NWS office.
SPI values for seven time periods for Hawaiian Island stations

On other Pacific Islands (maps — Micronesia, Marshall Islands, basinwide), August was drier than normal for Lukonor, Majuro, and Pago Pago, but near to above normal for the rest of the stations. Total rainfall for the last 12 months (September 2011-August 2012) was near to above normal for all stations.


X
  • Percent of Normal Precip
  • Precipitation
  • Normals
Pacific Island Percent of 1981-2010 Normal Median Precipitation
Station NameSep
2011
Oct
2011
Nov
2011
Dec
2011
Jan
2012
Feb
2012
Mar
2012
Apr
2012
May
2012
Jun
2012
Jul
2012
Aug
2012
Sep 2011-
Aug 2012
Chuuk118%97%136%125%57%181%107%40%173%131%141%169%122%
Guam NAS129%135%83%103%162%94%215%121%224%107%66%179%130%
Kapingamarangi107%57%81%124%109%71%121%102%143%179%146%192%122%
Koror266%12%62%97%36%126%121%120%122%95%88%102%102%
Kosrae104%154%95%174%65%185%60%84%86%99%124%144%112%
Kwajalein111%125%130%84%134%114%84%68%161%117%120%95%114%
Lukonor156%56%154%251%86%124%135%76%106%125%82%73%116%
Majuro115%115%119%91%107%65%194%97%59%81%68%87%98%
Pago Pago29%137%157%75%61%98%131%90%126%115%105%59%100%
Pohnpei115%77%123%110%82%138%98%45%115%100%92%96%97%
Saipan68%140%57%110%77%183%35%33%166%118%77%135%104%
Yap156%101%112%116%33%117%185%89%142%99%84%128%113%
Pacific Island Precipitation (Inches)
Station NameSep
2011
Oct
2011
Nov
2011
Dec
2011
Jan
2012
Feb
2012
Mar
2012
Apr
2012
May
2012
Jun
2012
Jul
2012
Aug
2012
Sep 2011-
Aug 2012
Chuuk13.7611.1414.4414.015.7413.138.875.0219.5615.2716.9221.78159.64
Guam NAS16.3715.456.145.246.502.854.453.057.636.636.7426.42107.47
Kapingamarangi10.644.637.5412.199.946.6113.8213.9117.2424.6820.6515.57157.42
Koror31.351.397.0410.793.6510.819.038.7914.4916.5416.3613.72143.96
Kosrae14.8216.8313.0728.1110.8923.939.5914.7015.3514.5618.5520.46200.86
Kwajalein11.9514.0014.685.594.223.011.973.5810.828.0811.839.2398.96
Lukonor15.796.3814.0228.347.2211.0612.518.6012.3514.5313.0810.26154.14
Majuro12.8714.6515.9710.378.274.4612.759.145.968.897.5410.15121.02
Pago Pago1.9212.6715.919.698.1411.7614.008.4112.156.135.843.19109.81
Pohnpei14.4411.7418.2117.6110.7513.1712.928.3122.9814.8614.2113.62172.82
Saipan6.9114.903.224.231.964.750.660.883.964.266.8617.7370.32
Yap21.0312.329.929.912.116.098.435.0011.1411.9512.7418.92129.56
Pacific Island 1981-2010 Normal Median Precipitation (Inches)
Station NameSep
2011
Oct
2011
Nov
2011
Dec
2011
Jan
2012
Feb
2012
Mar
2012
Apr
2012
May
2012
Jun
2012
Jul
2012
Aug
2012
Sep 2011-
Aug 2012
Chuuk11.7111.5110.6111.2510.107.258.3212.4711.3011.6611.9812.86131.02
Guam NAS12.6611.447.385.114.013.032.072.533.406.1810.1414.7482.69
Kapingamarangi9.938.199.279.849.159.2711.4313.6412.0813.7814.158.13128.86
Koror11.7711.8411.3911.1610.188.567.447.3211.8317.4818.5313.50141
Kosrae14.2210.9413.8316.1116.6712.9316.0617.5117.7514.6414.9114.22179.79
Kwajalein10.7411.1811.286.663.162.642.355.266.726.939.879.7486.53
Lukonor10.1511.329.0811.278.418.939.2611.3111.6911.6515.9314.04133.04
Majuro11.1712.7313.4411.397.746.886.589.4210.1111.0111.1711.69123.33
Pago Pago6.539.2610.1412.8413.3412.0010.689.399.665.335.555.38110.1
Pohnpei12.5515.2714.8316.0813.189.5513.1718.4119.9614.8115.4314.26177.5
Saipan10.0910.625.613.852.532.591.892.632.383.628.9113.1367.85
Yap13.5012.188.838.516.395.194.565.637.8512.0415.0814.82114.58

SPI values for seven time periods for Pacific Islands, computed by the Honolulu NWS office.
SPI values for seven time periods for Pacific Islands

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State/Regional/National Moisture Status
A detailed review of drought and moisture conditions is available for all contiguous U.S. states, the nine standard regions, and the nation (contiguous U.S.):

States
alabama arizona arkansas california colorado connecticut
delaware florida georgia idaho illinois indiana
iowa kansas kentucky louisiana maine maryland
massachusetts michigan minnesota mississippi missouri montana
nebraska nevada new hampshire new jersey new mexico new york
north carolina north dakota ohio oklahoma oregon pennsylvania
rhode island south carolina south dakota tennessee texas utah
vermont virginia washington west virginia wisconsin wyoming

Regional
northeast u. s. east north central u. s. central u. s.
southeast u. s. west north central u. s. south u. s.
southwest u. s. northwest u. s. west u. s.

National
Contiguous United States

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Drought Indicators
The following indicators illustrate the drought conditions this month:

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Contacts & Questions
For additional, or more localized, drought information, please visit:

Global Snow & Ice

Sea Ice Extent

According to the National Snow and Ice Data Center (NSIDC), the Northern Hemisphere sea ice extent — which is measured from passive microwave instruments onboard NOAA satellites — averaged for August 2012 was 4.72 million square km (1.82 million square miles) 38.46 percent below average. This ranked as the smallest August sea ice extent in the 1979-2012 period of record. The previous smallest August Arctic sea ice extent occurred in 2007, at 5.36 million square km (2.07 million square miles). The difference in sea ice extent from this year and the previous record is nearly equivalent the land area of Texas. During August, the Arctic lost an average of 91,700 square km (35,400 square miles) of ice per day, the fastest observed loss for the month of August on record. August 2012 marks the 16th consecutive August and the 135th consecutive month with below-average Arctic sea ice extent. August Northern Hemisphere sea ice extent has decreased at an average rate of 10.2 percent per decade.

According to analysis by the NSIDC, during August, sea ice was below average across all regions of the Arctic, except the East Greenland Sea, where the ice extent was near average. The rapid ice loss for the month was dominated by large ice losses across the East Siberian and the Chukchi Seas, partially due to a large and strong cyclone which impacted the region early in August. The storm broke up a large portion of the ice sheet causing it to melt faster. The Northern Sea Route opened up by the middle of August, but the Northwest Passage remained closed at the end of the month.

On August 26th, the Arctic sea ice extent dropped to 4.10 million square km (1.58 million square miles), breaking the previous record low extent for the Arctic which occurred on September 18, 2007 at 4.17 million square km (1.61 million square miles). The combination of above-average temperatures for much of the Arctic and the large, cyclone which broke up large areas of the ice sheet, contributed to the new record low extent. By August 31st, the Arctic sea ice had dropped to 3.69 million square km (1.4 million square miles), with several weeks of melting still likely during the 2012 melt season. August 2012 marks the first time in the 1979-present period of record that Arctic sea ice has dropped below 4.0 million square km (1.54 million square miles).

August's PIOMAS Arctic Ice Anomaly
Sea Ice Volume Anomlay
Source: UW's Polar Ice Center

When using Arctic sea ice extent to monitor the state of sea ice conditions across the Arctic, no information is available on the thickness of the ice. To compensate for this, the Polar Science Center at the University of Washington developed a modeled dataset to measure the volume of Arctic sea ice using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS). According to the product’s documentation, sea ice volume is an important climate indicator. It depends on both ice thickness and extent and therefore more directly tied to climate forcing than extent alone. According to this dataset, Arctic sea ice volume reached a monthly low value during August 2012, at 4,400 km3, about 700 km3 below the previous record low for August which occurred in 2011. The August sea ice volume was 76 percent below the maximum value in 1979, 67 percent below average and 2.1 standard deviations below the trend. The August 2012 value was 200 km3 above the smallest Arctic sea ice volume for any month, which occurred in September 2011.

The August 2012 Southern Hemisphere sea ice extent was 18.36 million square km (7.09 million square miles), 1.57 percent above average and the fourth largest (30th smallest) August sea ice extent in the 1979-2012 period of record. Antarctic sea ice extent during August has increased at an average rate of 0.6 percent per decade, with substantial interannual variability. Antarctic sea ice will continue to expand during its annual growth cycle which typically ends in late September or early October.

For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page.

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Upper Air


Note: University of Alabama in Huntsville scientists advise that the AMSU channel 5 on the AQUA satellite, which has heretofore been the anchor-source of data in the construction of low- and mid-tropospheric temperatures (LT and MT) since 2002, was experiencing gradually increasing noise since 2009. However, a relatively rapid increase in noise in the recent few months to September 2012 generated clearly erroneous values. Therefore, beginning September 2012, these datasets (LT and MT) switched from AQUA to the AMSU channel 5 on NOAA-15 and NOAA-18, replacing AQUA data after 2009 in version 5.5.

Troposphere

Lower Troposphere

August Lower Troposphere
August Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.34 +0.61 Coolest 32nd 1992 -0.47 -0.85 +0.14 +0.25
Warmest 3rd 1998 +0.46 +0.83
RSS +0.16 +0.29 Coolest 25th 1992 -0.47 -0.85 +0.15 +0.27
Warmest 9th 1998 +0.47 +0.85
Ties: 2005
June-August Lower Troposphere
June–
August
Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.33 +0.59 Coolest 31st 1992 -0.37 -0.67 +0.13 +0.24
Warmest 4th 1998 +0.47 +0.85
RSS +0.21 +0.38 Coolest 30th 1985 -0.38 -0.68 +0.14 +0.26
Warmest 5th 1998 +0.50 +0.90
Year-to-Date Lower Troposphere
January–
August
Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.19 +0.34 Coolest 29th 1985 -0.31 -0.56 +0.13 +0.23
Warmest 6th 1998 +0.53 +0.95
RSS +0.07 +0.13 Coolest 24th 1985 -0.39 -0.70 +0.13 +0.24
Warmest 11th 1998 +0.54 +0.97

Mid-troposphere

August Mid-troposphere
August Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.20 +0.36 Coolest 29th 1992 -0.32 -0.58 +0.08 +0.15
Warmest 6th 2010 +0.43 +0.77
RSS +0.13 +0.23 Coolest 25th 1992 -0.32 -0.58 +0.10 +0.19
Warmest 9th 1998 +0.44 +0.79
Ties: 2006
UW-UAH +0.28 +0.50 Coolest 30th 1992 -0.50 -0.90 +0.14 +0.25
Warmest 4th 1998 +0.53 +0.95
Ties: 2011
UW-RSS +0.18 +0.32 Coolest 26th 1992 -0.49 -0.88 +0.15 +0.27
Warmest 9th 1998 +0.54 +0.97
June-August Mid-troposphere
June–
August
Anomaly Rank
(out of 34 years*)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.19 +0.34 Coolest 29th 1989 -0.26 -0.47 +0.07 +0.13
Warmest 6th 1998 +0.45 +0.81
RSS +0.12 +0.22 Coolest 26th 1985 -0.35 -0.63 +0.09 +0.17
Warmest 8th 1998 +0.48 +0.86
Ties: 2006
UW-UAH +0.26 +0.47 Coolest 31st 1992 -0.39 -0.70 +0.13 +0.23
Warmest 4th 1998 +0.55 +0.99
UW-RSS +0.18 +0.32 Coolest 28th 1985 -0.39 -0.70 +0.14 +0.25
Warmest 7th 1998 +0.56 +1.01
RATPAC* +0.07 +0.13 Coolest 42nd 1965 -0.81 -1.46 +0.16 +0.28
Warmest 14th 1998 +0.59 +1.06

*RATPAC rank is based on 55 years of data

Year-to-Date Mid-troposphere
January–
August
Anomaly Rank
(out of 34 years*)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.03 +0.05 Coolest 19th 1989 -0.27 -0.49 +0.04 +0.07
Warmest 14th 1998 +0.53 +0.95
Ties: 2004, 1981
RSS 0.00 0.00 Coolest 17th 1989 -0.28 -0.50 +0.08 +0.14
Warmest 18th 1998 +0.53 +0.95
UW-UAH +0.10 +0.18 Coolest 27th 1989 -0.33 -0.59 +0.10 +0.18
Warmest 8th 1998 +0.62 +1.12
UW-RSS +0.06 +0.11 Coolest 22nd 1989 -0.33 -0.59 +0.13 +0.23
Warmest 13th 1998 +0.61 +1.10
RATPAC* +0.04 +0.07 Coolest 42nd 1965 -0.89 -1.60 +0.15 +0.27
Warmest 14th 2010 +0.58 +1.04

*RATPAC rank is based on 55 years of data

Stratosphere

August Stratosphere
August Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH -0.43 -0.77 Coolest 8th 2007 -0.56 -1.01 -0.37 -0.66
Warmest 27th 1991 +1.29 +2.32
RSS -0.37 -0.67 Coolest 6th 1996 -0.49 -0.88 -0.26 -0.47
Warmest 28th 1991 +1.17 +2.11
Ties: 2011
June-August Stratosphere
June–
August
Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH -0.37 -0.67 Coolest 8th 1996 -0.53 -0.95 -0.35 -0.63
Warmest 26th 1982 +1.10 +1.98
Ties: 2009
RSS -0.33 -0.59 Coolest 7th 1996 -0.48 -0.86 -0.27 -0.48
Warmest 28th 1982 +0.99 +1.78
Year-to-Date Stratosphere
January–
August
Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH -0.46 -0.83 Coolest 1st 2012 -0.46 -0.83 -0.35 -0.64
Warmest 34th 1983 +1.03 +1.85
RSS -0.44 -0.79 Coolest 1st 2012 -0.44 -0.79 -0.28 -0.51
Warmest 34th 1992 +0.99 +1.78

Background Information

Temperatures above the Earth's surface are measured within the lower troposphere, middle troposphere, and stratosphere using in-situ balloon-borne instruments (radiosondes) and polar-orbiting satellites (NOAA's TIROS-N). The radiosonde and satellite records have been adjusted to remove time-dependent biases (artificialities caused by changes in radiosonde instruments and measurement practices as well as changes in satellite instruments and orbital features through time). Global averages from radiosonde data are available from 1958 to present, while satellite measurements date back to 1979.

The mid-troposphere temperatures are centered in the in the atmospheric layer approximately 3–10 km [2–6 miles] above the Earth's surface, which also includes a portion of the lower stratosphere. (The Microwave Sounding Unit [MSU] channel used to measure mid-tropospheric temperatures receives about 25 percent of its signal above 10 km [6 miles].) Because the stratosphere has cooled due to increasing greenhouse gases in the troposphere and losses of ozone in the stratosphere, the stratospheric contribution to the tropospheric average, as measured from satellites, creates an artificial component of cooling to the mid-troposphere temperatures. The University of Washington (UW) versions of the UAH and RSS analyses attempt to remove the stratospheric influence from the mid-troposphere measurements, and as a result the UW versions tend to have a larger warming trend than either the UAH or RSS versions. For additional information, please see NCDC's Microwave Sounding Unit page.

The radiosonde data used in this global analysis were developed using the Lanzante, Klein, Seidel (2003) ("LKS") bias-adjusted dataset and the First Difference Method (Free et al. 2004) (RATPAC). Additional details are available. Satellite data have been adjusted by the Global Hydrology and Climate Center at the University of Alabama in Huntsville (UAH). An independent analysis is also performed by Remote Sensing Systems (RSS) and a third analysis has been performed by Dr. Qiang Fu of the University of Washington (UW) (Fu et al. 2004)** to remove the influence of the stratosphere on the mid-troposphere value. Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.

References

Wildfires

Updated: 7 September 2012


Overview

During August, numerous large fires occurred across the western and central U.S. regions as dryness, low humidity, and windy conditions persisted. The monthly average fire size reached 523.4 acres per fire—which was the highest for any August in the 2000-2012 record. Likewise, the year-to-date average fire size of 173.5 acres was the most since 2000. The monthly total of 3.64 million acres burned by wildfires ranked as the highest for any August since 2000. Moreover, nearly half the entire acreage burned since January occurred within the single month of August and brought the year-to-date total acreage burned to the most on record—exceeding 7.72 million acres. The monthly total number of 6,948 fires was the 2nd least for August in the thirteen-year record. Similarly, both the total number of fires for the season (22,232) and year-to-date (44,524) ranked as 2nd least since 2000—denoting a tendency for fires, although fewer in number, to be larger in size.

1-Month Wildfire Statistics*
August Totals Rank
(out of 13 years)
Record 2000-2010
Average
Value Year
Acres Burned 3,636,606 Most on Record 3,636,606 2012 1,890,173
13ᵗʰ Least
Number of Fires 6,948 12ᵗʰ Most 11,217 2000 9,160
2ⁿᵈ Least
Acres Burned per Fire 523.4 Most on Record 523.4 2012 207.3
13ᵗʰ Least
3-Month Wildfire Statistics*
June–August Totals Rank
(out of 13 years)
Record 2000-2010
Average
Value Year
Acres Burned 7,014,294 2ⁿᵈ Most 7,022,570 2005 4,335,639
12ᵗʰ Least
Number of Fires 22,232 11ᵗʰ Most 37,103 2006 26,767
3ʳᵈ Least
Acres Burned per Fire 315.5 2ⁿᵈ Most 343.8 2005 167.8
12ᵗʰ Least
Year-to-Date Wildfire Statistics*
January–August Totals Rank
(out of 13 years)
Record 2000-2010
Average
Value Year
Acres Burned 7,724,955 Most on Record 7,724,955 2012 5,395,390
13ᵗʰ Least
Number of Fires 44,524 12ᵗʰ Most 78,948 2006 59,174
2ⁿᵈ Least
Acres Burned per Fire 173.5 Most on Record 173.5 2012 91.4
13ᵗʰ Least

*Data Source: The National Interagency Fire Center (NIFC)

Discussion

The above-normal fire weather potential of the Intermountain West was realized as the hot, dry conditions persisted and thunderstorms triggered wildfires across dried out higher-elevation fuels. Nevada experienced its warmest August on record (1895-2012) while Colorado and Wyoming experienced their warmest summers since 1895. Meanwhile, monthly temperatures were below normal at locations within the northern Great Plains states where conditions remained dry. In central Nebraska, exceptional drought conditions expanded westward to reach northeastern Colorado. Wildfires flared within Nebraska and Wyoming during late August, where both states observed their driest summers since 1895. Late in the month, Hurricane Isaac's slow track over the south central region of the U.S. drenched areas of Mississippi, Louisiana, Arkansas, and parts of Texas, Tennessee, and Oklahoma. As a result, Mississippi and Louisiana each sustained their second wettest August on record (1895-2012). However, the copious rains fell mostly outside of the predominant wildfire-prone areas. Please see the U.S. temperature and precipitation report for additional information.

Drought area increased across most of the central and western states with extreme to exceptional drought over much of the central Rockies, the Plains, and through the Mississippi and Ohio valleys. Between August 7th and August 14th, the Exceptional Drought (D4) conditions in the U.S. Southern Plains expanded notably. Drought areas in Colorado, Kansas, and Oklahoma merged with those in Arkansas to span across central Kansas through Missouri. According to the August 28, 2012, U.S. Drought Monitor nearly 63 percent of the contiguous U.S. as affected by moderate to exceptional drought.

Significant Events


Please note, this is a list of select fires that occurred during August. Additional fire information can be found through Inciweb.


California

Several wildfires remained active in northern California, following a rash of blazes across the entire state at mid-month.

The Chips wildfire which burned the entire month, destroyed over 75,000 acres, and exceeded suppression costs of $44.2 million U.S. dollars. The blaze ignited on July 29th and contained as of August 31st, was confined to a rugged, remote area of Plumas National Forest, and nine structures were lost.

The Ponderosa wildfire—the next costliest incident to contain during August at $27.6 million U.S. dollars—scorched nearly 27,700 acres of rugged, densely forested land since being sparked by lightning on August 18th. At least 52 homes and more than 80 other structures were destroyed in the blaze while seven persons were injured.

The North Pass wildfire, also ignited by lightning on August 18th, remained active throughout the month with over 70 percent containment achieved as of September 7th. Suppression costs have reached $16.7 million U.S. dollars and nearly 42,000 acres have burned. Seven residences and nine outbuildings have been destroyed, and three times as many homes and buildings remained threatened. Nine people were injured and evacuations were in effect for parts of Mendocino County as the fire continued spreading northward at month's end.

Two California border wildfires incurred around $15 million U.S. dollars apiece in estimated suppression costs during August. The Forts Complex (a three-fire incident) burned areas of a designated wilderness area shared with Oregon while the Rush Fire crossed into Nevada.

The Forts Complex consisted of three fires—the Hello Fire, Lick Fire, and Goff Fire—sparked by lightning on August 5th. Firefighters exercised special care to protect the bio-diverse Red Butte wilderness as they battled flames on its steep terrain. The fires tended to leave the larger trees intact, while predominantly burning the underbrush across more than 22,300 acres. Only 30 percent contained at month's end, the fires resulted in evacuation of 300 residents, and 80 homes were under threat while eight injuries had been reported.

Ravaging more than 315,500 acres altogether, the Rush Fire became one of the largest western fires during the month. Having been ignited by lightning on August 12th, the flames—being fanned by gusty winds in the following days—rapidly spread through dry vegetation. The fire which burned almost 272,000 acres in northeastern California constituted the second largest in the state since 1932. The fire also burned over 43,600 acres in Nevada where it posed a threat to a major natural gas line and power transmission lines at mid-month. The fire which was contained on August 30th, adversely impacted the natural habitats for federally-protected wild horses, burros, and grouse of the area.

Idaho

Multiple fires raged in Idaho during August. Heavy smoke from the various fires resulted in air quality (AQ) advisories being issued for area residents, reaching to the AQ index's second-highest level (purple) in terms of the health effects severity by the end of the month. The Halstead Fire which was ignited by lightning on July 27th, charred over 140,000 acres while sweeping quickly through beetle-killed lodgepole pines in the Salmon-Challis National Forest and remained active in September.

The Mustang Complex (consisting of five fires) was ignited during thunderstorms and lightning in late July and remained active throughout August, and eventually advanced into Montana's Bitterroot National Forest. As of September 7th, the blazes had engulfed nearly 253,000 acres of dead lodgepole pines as well as Ponderosa pines with grass and brush understory at lower elevations.

The Trinity Ridge Fire that began August 3rd, scorched around 146,000 acres through August and remained uncontained. The flames of this crown fire engulfed timber stands of pines and fir. At least eight structures were destroyed and residents of Featherville were evacuated during August.

Monthly Wildfire Conditions

Wildfire information and environmental conditions are provided by the National Interagency Fire Center (NIFC) and the U.S. Forest Service (USFS) Wildland Fire Assessment System (WFAS).

Light rainfalls over the southwestern U.S. during the first week of August impeded the wildfire development conditions somewhat. Twenty-five large wildfires were active on August 1st, mostly concentrated in two areas—northern Idaho and central Montana, and northern Texas and central Oklahoma. The fires coincided closely with areas of dry fuels having dangerously low 10-hour and 100-hour fuel moisture values (below 10 percent in the West and Central states). Fires occuring in Arkansas and Louisiana aligned with extreme fire potential indicated by the Keetch-Byram Drought Index (KBDI) values over 700. Much of the western U.S. had 1000-hr fuel moistures below 15 percent during the entire month. Wildfires in Oklahoma rendered tragic consequences with over 120 structures lost statewide due to dozens of grassland fires early in the month, including five major ones. Close to 25 homes and a day care center were destroyed in the town of Luther. The fire near the town of Mannford, which engulfed nearly 64,000 acres and consumed close to 40 structures,was deemed the largest in recent state history, according to media reports. Near the city of Norman, where one person perished in the fire, at least 17 families received refuge in shelters established by the American Red Cross. At least two wildfires in northern Texas were fueled by drought-stressed brush, mesquite, and juniper and forced evacuation of at least 40 homes. Windy conditions spread the Rhodes Ranch II blaze which ignited August 7th and consumed close to 2,000 acres before being contained on August 16th. The Dark Valley fire began August 9th, and scorched over 1,700 acres prior to containment on August 17th.


The number of wildfires swelled to at least 69 incidents as of August 15th. As the quantity of fires increased within the existing locations, pockets of new fires erupted along Nevada's borders—Oregon in its north, Arizona and Utah in its south—as well as across California at mid-month. Precipitation over the central U.S. slightly improved the respective 10-hour and 100-hour fuel moistures of those areas. The 100-hour fuel moistures worsened over the Four-Corners region, particularly in north-central Arizona. Lightning sparked the Charley Fire in central Arizona which burned 2,300 acres of short grass over extremely steep terrain from August 12th through August 20th. Precipitation of 0.39 inche (9.9 mm) falling on August 19th facilitated the wildfire's containment. Another lightning-sparked wildfire burned about 360 acres near the Grand Canyon National Park in northwestern Arizona from August 13th to August 22nd. Fuels included short grass and brush. The Quail Fire endangered parts of the Joshua Tree National Park in southern California between August 12th and August 15th. The fuels of piñon, juniper, scrub oak, blackbrush, cactus, and desert grasses constitute the habitat for the desert tortoise, a threatened species. Nearly 280 acres of the Park's designated wildness area were burned in the lightning-sparked blaze.


By August 31st, large fire activity was primarily constrained to the northwestern U.S. with the exception of one wildfire in eastern Texas, and the areas coincided with moderate moisture deficits as indicated by the KBDI values from 400-700. The Delphia wildfire blazed more than 400,600 acres in central Montana between August 24th and August 31st. Gusty winds drove the flames through fuels of timber, sage, and grass and suppression costs topped $2.0 million U.S. dollars. Although summer monsoon rains brought respite to dry fuels in the Desert Southwest as evidenced in the 10-hour fuel moisture, the dryness for the High Plains intensified. For New Mexico, the August rainfall signified its driest 18-month consecutive period on record. The influx of tropical rainfall associated with Hurricane Isaac significantly improved the 10-hour and 100-hour fuel moistures in the Mid-South, notably Arkansas and Missouri.

Alaska's 1000-hour fuel moisture indicators reflected continuous improvement throughout the month. Both the 10-hour and 100-hour fuel moistures initially worsened, with dryness expanding over most of the state at mid-month. Drenching rains from multiple storms the latter half of August yielded widespread improvement for all Alaskan dry fuels by the month's end.


All Fire Related Maps


Citing This Report

NOAA National Climatic Data Center, State of the Climate for August 2012, published online September 2012, retrieved on April 19, 2014 from http://www.ncdc.noaa.gov/sotc/2012/8.