Entire Report - July 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:



July Extreme Weather/Climate Events

Supplemental July and January-July Information



Alaska Temperature and Precipitation:

  • Alaska had its 18th coolest July since records began in 1918, with a temperature 1.8°F (1.0°C) below the 1971–2000 average.
  • Alaska had its 23rd coolest May-July since records began in 1918, with a temperature 1.3°F (0.7°C) below the 1971–2000 average.
  • Alaska had its 15th coolest January-July since records began in 1918, with a temperature 2.5°F (1.4°C) below the 1971–2000 average.
  • Alaska had its 8th wettest July since records began in 1918, with an anomaly that was 50.0 percent above the 1971–2000 average.
  • Alaska had its 4th wettest May-June since records began in 1918, with an anomaly that was 27.6 percent above the 1971–2000 average.
  • Alaska had its 23rd wettest January-July since records began in 1918, with an anomaly that was 16.6 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)
  • It was the seventh warmest July since 1895 in the Northeast. The average temperature was 72.8 degrees F (22.7 degrees C), which was 2.9 degrees (1.61 degrees C) above normal. Each of the twelve states in the region averaged warmer than normal, with departures that ranged from +1.5 degrees F (0.83 degrees C) in Rhode Island to +4.0 degrees F (2.22 degrees C) in Delaware. It was the second warmest July since 1895 in Delaware and the third warmest in Maryland. All twelve states in the region ranked within the top 24 warmest since recordkeeping began in 1895. New maximum temperature records were set at many of the region’s first order stations during the month as the mercury soared into the upper 90’s and low 100’s (32 - 40 degrees C). The sensor at Washington’s National Airport recorded 105 degrees F (40.6 degrees C) on the 7th, surpassing the record of 102 degrees F (38.9 degrees C) set just two years ago. Baltimore, MD’s new record temperature of 104 degrees F (40.0 degrees C) on the 18th broke the long-standing record of 102 degrees F (38.9 degrees C) set in 1887. The Northeast’s seven-month average (January July) of 49.9 degrees F (9.9 degrees C) was the warmest such period since 1895. It was the 2nd warmest January through July in Pennsylvania and West Virginia and the warmest first seven months of the year in the rest of the Northeast states. The most recent twelve months (August 2011 through July 2012) was the warmest August through July in 117 years in the Northeast and in all of the states except West Virginia. It was the second warmest August through July in West Virginia where the average temperature of 54.7 degrees F (12.6 degrees C) missed tying the record set in 1932 by 0.1 degree F (0.06 degrees C).
  • With a regional precipitation total of 3.70 inches (94 mm), the Northeast averaged 87 percent of normal in July. Three states, Pennsylvania, (107 percent), Rhode Island (116 percent) and West Virginia (125 percent) had totals that were wetter than normal. Departures in the drier-than-normal states ranged from 87 percent in Connecticut to 51 percent in Maine. Interestingly, last month, Maine saw its 4th wettest June since 1895; this month the state had its 5th driest July on record. And last month’s dry state, West Virginia, which ranked 11th driest in June ended up having its 10th wettest July in 118 years. The year-to-date totals averaged 88 percent of normal in the Northeast. It was the driest January through June since 1895 in Delaware and the 5th driest in Maryland. While drought conditions in the Northeast were not as bad as some parts of the country, there were areas of concern according to the July 31, 2012 U. S. Drought Monitor. Western Massachusetts, a small area in north central Connecticut, and parts of upstate New York were experiencing moderate drought (D1) conditions while areas of severe drought (D2) expanded in Delaware and eastern Maryland. Areas of abnormally dry (D0) conditions expanded in most of the states in the region, the exception was West Virginia, where conditions improved by month’s end.
  • Severe storms on the 26th produced five EF1 tornadoes, two in Steuben County, NY, one in Chemung County, NY, one in Luzerne County, PA and one in Susquehanna County, PA. The Chemung County tornado ripped through Elmira, downing power lines and trees, resulting in damage to about 300 homes and businesses. The other tornadoes formed over more rural areas, causing minor structural damage from fallen trees or wind blown debris. In addition, several microbursts resulted in straight-line damage near Orwell and Harford, PA. Over 600 trees were downed near Orwell and minor structural damage was reported in Harford.
  • For more information, please go to the Northeast Regional Climate Center Home Page.
  • Midwest Region: (Information provided by the Midwest Regional Climate Center)
  • Average July temperatures were the warmest in decades in the Midwest. Preliminary numbers for the month rank all nine states among the top five since 1895. It was the warmest July in Missouri since 1980, in Michigan since 1955, in Illinois, Indiana, Iowa, Kentucky, and Minnesota since 1936, in Ohio since 1934, and in Wisconsin since 1921. Temperatures across the region averaged 2 degrees F (1 C) to 8 degrees F (4 C) above normal. Maximum daily temperatures were 7 to 10 degrees F (4 to 6 C) above normal across most of Missouri, Illinois, Indiana, Iowa, and southern Wisconsin. Record high temperatures were set at more than 100 stations on 15 of the 31 days in the month with the monthly record count topping 3000.
  • July precipitation ranged from just a trace amount in western Iowa to more than 10 inches (254 mm) in eastern Kentucky. Precipitation departures of 2 to 4 inches (51 to 102 mm) were common over an area bounded by central Indiana on the east and from southwest Minnesota to southwest Missouri on the west. Kentucky and Michigan had statewide totals above normal. Minnesota, Wisconsin, and Ohio had statewide totals slightly below normal and Indiana fell about 1.50 inches (38 mm) below normal. Missouri had 1.58 inches (40 mm) statewide ranking it as the 7th driest July since 1895. Illinois had 1.46 inches (37 mm) ranking 4th driest and Iowa had 1.21 inches (31 mm) ranking 3rd driest since 1895. It was the driest July in Iowa since 1975, in Missouri since 1970, and in Illinois since 1936.
  • Drought expanded and intensified in the Midwest during July. The percentage of the region in drought went from less than 50% to more than 70% during July. Severe drought areas tripled in size from 15% to 55% while areas in extreme or exceptional drought (the highest two categories of drought) grew from just over 5% to more than 31%.
  • Crop conditions continued to deteriorate during the month due to the heat and drought. Large portions of the Midwest corn and bean growing areas were in drought. Conditions deteriorated such that more than 40% of the corn crop was categorized as very poor or poor in each state except Minnesota. Beans were fairing slightly better but still reported over 30% of the crop as very poor or poor in every state except Minnesota. In Missouri, over 80% of the corn and 70% of the bean crop were rated very poor or poor.
  • 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 in July were above normal across most of the Southeast region. The greatest departures (3 to 4 degrees F (1.6 to 2.2 degrees C)) extended from central South Carolina to northern Virginia, while much of Georgia, Alabama, northern Florida, Puerto Rico, and sections of the Atlantic coast were between 1 and 2 degrees F (0.5 to 1.1 degrees C) above normal for the month. Temperatures across much of the Florida Peninsula and the U.S. Virgin Islands were near normal to slightly below normal for the month. It was the warmest July on record at Roanoke, VA, and Wilmington, NC, in records extending back to 1912 and 1870, respectively. Several other locations recorded one of their top 5 warmest July’s on record, including Washington D.C., Richmond, VA, Raleigh-Durham, NC, Charlotte, NC, Columbia, SC, Charleston, SC, and Atlanta, GA. The heat wave that began at the end of June extended into the first week of July, with more record-breaking temperatures observed across the Southeast. All-time maximum temperature records of 108 degrees F (42.2 degrees C) and 107 degrees F (41.7 degrees C) were set on the 1st of the month at Macon, GA, and Greenville-Spartanburg, SC, respectively. Charlotte, NC tied its all-time maximum temperature of 104 degrees F (40 degrees C) on the 1st, while Raleigh-Durham, NC tied its all-time maximum temperature of 105 degrees F (40.6 degrees C) on the 8th of the month. Monthly maximum temperature records of 105 degrees F and 108 degrees F were tied on the 1st of the month at Atlanta, GA, and Athens, GA, respectively. More generally, temperatures exceeding 100 degrees F (37.8 degrees C) were observed at several locations throughout the first week of the month, particularly across the northern half of the region. Reagan International Airport reached 105 degrees F on the 7th of the month, which came within 1 degree F (0.5 degrees C) of the highest July temperature recorded in the Washington D.C. area (period of record 1871-2012). Anomalously warm temperatures were also observed across the higher elevations of western North Carolina. Mount Mitchell, NC recorded a maximum temperature of 80 degrees F (26.7 degrees C) on the 1st and 2nd of the month, which came within 1 degree of the all-time maximum temperature recorded at the summit (period of record 1980-2012).
  • Monthly precipitation was above average across northern sections of Alabama, Georgia, and South Carolina and across much of North Carolina, where monthly totals between 5 and 10 inches (127 and 254 mm) were observed. Some precipitation totals across western and eastern North Carolina exceeded 10 inches for the month, which is between 150 and 300 percent of normal. Mount Mitchell, NC recorded its 2nd wettest July on record with 11.32 inches (287.5 mm), while New Bern, NC recorded 11.13 inches (282.7 mm) for the month, which is more than four inches (101.6 mm) above normal (period of record 1948-2012). Montevallo, AL, located south of Birmingham, recorded 5.60 inches (142.2 mm) of rainfall on the 31st of the month, which broke the previous 24-hr rainfall total in July by over two inches (50.8 mm) (period of record 1893-2012). July was also a wet month across Puerto Rico, especially along the northern and southern slopes, where precipitation was more than 200 percent of normal. In contrast, the driest locations (between 25 and 75 percent of normal) were found across much of Virginia, Florida, and southern sections of Alabama, Georgia, and the Carolinas. Wilmington, NC (period of record 1870-2012), and Orlando, FL (period of record 1892-2012), recorded their 5th driest July on record with 2.3 inches (58.4 mm) and 1.3 inches (33 mm) of rainfall, respectively.
  • There were 1,832 reports of severe weather across the Southeast in July, with at least one report on 30 of the 31 days. This is the second greatest number of severe weather reports for any month in the Southeast region since 2000 (greatest number is 1,877 in April 2011). Thunderstorm activity was fairly widespread across northern Georgia and across the Carolinas, resulting in numerous reports of wind damage. Some of these storms also produced large hail and contributed to scattered power outages and some lightning-induced house fires. There were seven preliminary tornado reports, of which six have so far been confirmed. On the 10th of the month, an EF-0 tornado was confirmed in Hyde County, NC along Highway 264 near Palmico Sound. No damage was reported. On the 14th of the month, an EF-0 tornado touched down in a rural part of Accomack County, VA along the Delmarva Peninsula. Numerous trees were damaged or felled over its 0.5 mile (0.8 km) path. On the 29th of the month, an EF-1 tornado tracked for approximately two miles (3.2 km) across northern Wakulla County, FL where some damage to buildings and homes was observed. Waterspouts were observed moving inland near Brunswick, GA on the 18th of the month and near the Bodie Island Lighthouse along the Outer Banks in Dare County, NC on the 30th of the month. No damage was reported and both were given EF-0 ratings. Another waterspout was reported near Roanoke Island in Dare County, NC and was given an EF-0 rating.
  • The beneficial rainfall across the central portion of the region helped reduce or stabilize drought conditions during the month, but led to an increase in insect and fungal disease pressures among several crops. By the end of July, much of central North Carolina was drought-free. In contrast, the relative lack of rain across Virginia resulted in an expansion of abnormally-dry conditions (D0) and the emergence of moderate drought (D1) across central and eastern parts of the Commonwealth. There was a re-emergence of moderate drought across parts of the western Florida Panhandle and northern Alabama, while areas of extreme (D3) and exceptional (D4) drought expanded slightly across west-central Georgia, which missed out on the beneficial rains to the north. Several fields remained flooded across the Florida Panhandle from the heavy rains back in June, which prevented some harvest of corn early in the month. However, by the end of July much of the water had subsided, allowing farmers to prepare fields for the planting of fall vegetables. The continued warm and dry weather across much of Georgia resulted in a successful peach season that ended a full three weeks earlier than normal. In fact, overall yields for many crops in Georgia remained ahead of their 5-year average.
  • 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)
  • Hot and dry conditions continued this July across the majority of the High Plains Region. The larger temperature departures occurred in northeastern Wyoming, southern and eastern South Dakota, northern and eastern Nebraska, and central and eastern Kansas where the departures from normal temperature ranged from 6.0-8.0 degrees F (3.3-4.4 degrees C) above normal. There were even a few pockets of eastern Kansas, northern Nebraska, and eastern South Dakota which had temperature departures which were 8.0-10.0 degrees F (4.4-5.6 degrees C) above normal. No station in the Region had monthly average temperatures which were below normal and the continued warm pattern caused many locations across the Region to be ranked in the top 10 warmest Julys on record. One location was Denver, Colorado which had its warmest July on record with an average temperature of 78.9 degrees F (26.1 degrees C). This was 4.7 degrees F (2.6 degrees C) above normal (period of record 1872-2012). The previous record occurred in 1934 with an average temperature of 77.8 degrees F (25.4 degrees C). Interestingly, this was also the warmest month ever recorded in Denver. The previous record also occurred in July 1934. So far this year, Denver has had 13 days at or above 100 degrees F (37.8 degrees C), with 7 of those occurring this month. Previously, the most days at or above 100 degrees F (37.8 degrees C) was 7 in 2005. Again, this month was just one more month of continued warmth as most of the Region had warmer than normal temperatures each month this year. Eastern portions of the Region have had January-July average temperatures which were 6.0-8.0 degrees F (3.3-4.4 degrees C) above normal. Many locations in this portion of the Region have had the warmest January-July period on record. One of these locations was Topeka, Kansas which had a January-July average temperature of 62.1 degrees F (16.7 degrees C). This was 7.5 degrees F (4.2 degrees C) above normal and easily beat the old record of 58.9 degrees F (14.9 degrees C) set in 1946 (period of record 1887-2012). The continued hot and dry conditions have taken their toll on many crops and livestock across the Region and beyond. According to the U.S. Department of Agriculture, by the end of the month 88 percent of all corn, 87 percent of all soybeans, 64 percent of all hay acreage and 72 percent of all cattle were within an area experiencing drought conditions in the United States. Poor pastureland conditions in the High Plains Region have led to the early weaning of calves in some areas and even culling of herds. Some producers have decided to chop the drought damaged dryland corn for silage or hay due to the poor condition of the pastures, which have been providing little to no grazing capacity at this point. Conservation Reserve Program (CRP) acres have been released for emergency use in Colorado, Kansas, and Nebraska. In Colorado, irrigated crops have progressed ahead of schedule; however there were growing concerns over dwindling water reserves. Meanwhile, in Nebraska, irrigators were struggling with the water demands as surface water use was stopped due to low river levels. According to the National Agricultural Statistics Service (NASS), there were some cases in Nebraska where more water had been used by mid-July than what would normally be used in an entire season.
  • Precipitation was varied across the Region this month. Kansas, Nebraska, and South Dakota were hit the hardest by the dryness as the majority of each of those states received only 50 percent or less of normal precipitation. Northern and eastern North Dakota and central and eastern Wyoming also received precipitation which was only 50 percent of normal or less. Some locations in Nebraska did not receive any measurable precipitation this month. Norfolk, Nebraska was one of those locations and set a new record for driest July (period of record 1893-2012). To put this record into perspective, Norfolk normally receives over 3 inches (76 mm) of precipitation in July. The old record occurred in 1936 with 0.18 inches (5 mm). Ultimately, Norfolk went a total of 38 consecutive days without measurable precipitation which is quite unusual for this time of year. This ranked as the 14th longest stretch without measurable precipitation on record and was the longest stretch to occur solely in the summer months. The second longest stretch of days without measurable precipitation to occur only in the summer was a 28 day stretch ending on August 2, 1901 (this stretch ranks 51st). While large areas received little to no precipitation, central Colorado, northwestern South Dakota, and pockets of Wyoming received at least 150 percent of normal precipitation. Boulder, Colorado was one of the wetter locations with 4.99 inches (127 mm) precipitation. This amount of precipitation was 3.20 inches (81mm) above normal, or 279 percent of normal, and enough for Boulder to have its 3rd wettest July on record (period of record 1893-2012). The record set in 1919 held at 7.46 inches (189 mm). Although July was a relatively quiet severe weather month, an interesting event occurred on July 28th in the Rocky Mountains. According to the National Weather Service in Boulder, Colorado, an EF-0 tornado touched down approximately 1.75 miles northeast of Mount Evans. This tornado touched down at an estimated altitude of 11,900 feet (3627 m), making it the second highest altitude tornado on record. The highest tornado on record occurred on July 4, 2004 in the Sequoia National Park in California at 12,000 feet (3658 m).
  • Over the last month, there were major changes to the U.S. Drought Monitor as hot and dry conditions prevailed. These conditions led to a rapid expansion and deterioration of the drought. At the end of June, about 67 percent of the Region was under moderate (D1) to extreme (D3) drought. Unfortunately, at this end of this month, 87 percent of the Region was under drought, with 4 percent of the Region in the exceptional drought designation (D4). D4 areas included a small area of central Nebraska, a small area of southeastern Colorado, and much of western Kansas. The D3 areas expanded tremendously since last month to include nearly all of Kansas and Nebraska, and significant portions of Colorado, South Dakota, and Wyoming. There were even some areas of the Region which went from no drought to D3 in just a matter of weeks. According to the U.S. Seasonal Drought Outlook released July 19th, drought conditions were expected to improve slightly in Colorado and extreme southern Wyoming. Areas of drought in all other areas of the Region were expected to persist, while new areas of drought were expected to develop in the Dakotas.
  • For more information, please go to the High Plains Regional Climate Center Home Page.
  • Southern Region: (Information provided by the Southern Regional Climate Center)
  • With the exception of southern Louisiana, southeastern Texas, and the western Texas panhandle, the majority of the Southern Region experienced a slightly warmer than normal July. The highest temperature anomalies were observed in northeastern Oklahoma and northern Arkansas, where temperatures averaged anywhere from 4 to 8 degrees F (2.22 to 4.44 degrees C) above normal. In Tennessee, temperatures ranged between 4 and 6 degrees F (2.22 and 3.33 degrees C) above normal. Similar values were also observed in western Oklahoma and northern Texas. For Arkansas, it was the sixth warmest July on record (1895-2012) with a state wide average temperature of 84.10 degrees F (28.94 degrees C). Tennessee reported its seventh warmest July on record (1895-2012). The state wide average temperature for Tennessee was 80.40 degrees F (26.89 degrees C). Oklahoma averaged 85.50 degrees F (29.72 degrees C), which was their ninth warmest July on record (1895-2012). The other state wide average temperatures include: 82.10 degrees F (27.83 degrees C) in Louisiana, 81.80 degrees F (27.67 degrees C) in Mississippi, and 83.40 degrees F (28.56 degrees C) in Texas.
  • July precipitation in the Southern Region varied spatially such that the northeastern half of the region experienced a much drier than normal month, while the southeastern half of the region experienced a much wetter than normal month. In southern Louisiana, precipitation totals for the month averaged between 150 and 200 percent of normal. Similar values were observed throughout most of Mississippi, southeastern Texas, and eastern Tennessee. State average July precipitation totals were as follows: 2.86 inches (72.64 mm) in Arkansas, 7.72 inches (196.09 mm) in Louisiana, 7.03 inches (178.56 mm) in Mississippi, 1.25 inches (31.75 mm) in Oklahoma, 6.20 inches (157.48 mm) in Tennessee, and 2.72 inches (69.09 mm) in Texas. State precipitation rankings worth mentioning include Louisiana and Mississippi, which both experienced their eighteenth wettest July on record (1895-2012). Tennessee experienced its twentieth wettest July on record (1895-2012), and Oklahoma experienced its seventeenth driest July on record (1895-2012).
  • Drought conditions in the Southern Region have both improved and deteriorated. Improvements occurred in northern Louisiana, whereby now only a small area in the northeast is in drought. There was also a significant amount of improvement in eastern Tennessee, in that much of the central and eastern counties saw a one to two category improvement. Drought conditions in Mississippi remained fairly unchanged from last month. Due to heavy rainfall totals, eastern Texas experienced a one category improvement, and much of the southeastern part of the state is now drought free. Conditions in the remainder of the state are relatively equivalent to what was observed last month. In contrast, conditions did get worse in Arkansas. Over eighty percent of the state in now in extreme or exceptional drought. Drought has also worsened in Oklahoma, where over seventy percent of the state is now in extreme or exceptional drought, with the entire state being in moderate drought or worse.
  • Dry, and hot conditions in Oklahoma have made the state vulnerable to wildfires. According to KJRH News in Tulsa, Oklahoma, over 28,000 acres (113.31 square km) have been burned in a blaze in Kiowa County. Oklahoma Forestry Services reports that all counties in the state are under a burn ban.
  • In Texas, fires, driven by lightning and dry grasses, burned near Byers in Clay County and in McFadden Wildlife Refuge in Jefferson County; while the former was stopped before any significant damage was caused, the wildlife refuge saw at least 150 acres (0.61 square km) burned. Further, a fire reported at Bluff Creek has burned over 2700 acres (10.93 square km), though no monetary damage report has been issued. Elsewhere, country-wide drought issues are having an effect on ranchers, whose livestock numbers have dropped by 2% in the Panhandle due to elevated corn prices and less grazing acreage. Farmers’ losses have been mitigated somewhat by intermittent rainy conditions. Legislation aimed at further mitigating these effects by reducing the processing time for emergency declaration, reducing the emergency loan interest rate by 1.25 percent, and granting subsidies to various crop farmers. The Texas State Water Plan has plans written in it to pursue various projects, totaling $53 billion, to develop projects to bring water to various parts of the state that are seeing increased demand and competition for water from all sectors (Information provided by the Texas Office of State Climatology).
  • There was only one tornado report for the month in the Southern Region. There were no reports of injuries or damages. The twister occurred in Calcasieu Parish, near Lake Charles, Louisiana.
  • For more information, please go to the Southern Regional Climate Center Home Page.
  • Western Region: (Information provided by the Western Regional Climate Center)
  • A vigorous onset of the Southwest Monsoon this month provided much needed precipitation and relief from June heat for the desert Southwest and southern Great Basin. June temperature trends continued into July, with coastal regions slightly cooler than normal while inland locations recorded above normal to record-breaking temperatures.
  • Four monsoonal pushes into the Mojave Desert and southern Great Basin set record precipitation totals throughout the region. Lake Havasu City, Arizona, experienced its wettest July on record at 2.48 in (63 mm). Downpours on the evening of July 13th spurred flash floods in the area that swept away cars, damaged houses, and caused one fatality. Precipitation at Pahrump, Nevada totaled 1.74 in (44.2 mm), the second wettest July in a record dating back to 1914. Near the Nevada/Utah border, Caliente (2.48 in, 63 mm) and Pioche (2.88 in, 73.2 mm), Nevada experienced their third wettest Julys in records dating back to 1903 and 1888, respectively. However, south of there, Las Vegas has recorded less than an inch (0.71 in, 18.0 mm) since October 1, just 20 percent of average. Despite high July precipitation in some locations, by month’s end the USDA had declared natural disaster areas in all Nevada and eastern California counties due to severe and persistent drought. Mid-month, the remnants of Hurricane Fabio traveled northward over California and Nevada up to the Oregon/Idaho/Washington border. The moisture, combined with atmospheric instability, produced light rainfall that set daily records in many locations that typically receive little July precipitation.
  • Record monthly average temperature was set again this month at Denver, Colorado at 78.9 F (26 C); June 2012 also set the monthly average record at 75 F (23.8 C). Denver experienced 27 days over 90 F (32.2 C) this month, breaking the previous record of 26 days set in 2000 and 2008. Records at Denver date back to 1872. Elsewhere in Colorado, Pueblo experienced 14 days of triple digit (F) temperatures (> 37.8 C) from June 22 through July 5. This shattered the previous record of 9 days. Further south, Beaver Dam, Arizona, recorded its all-time high of 121 F (49.4 C) on July 10. Records at Beaver Dam began in 1951. On the morning of July 12, temperatures at Death Valley, California dropped to a minimum of 107 F (41.7 C), the second highest low temperature since records began in 1911. The record highest low stands at 110 F (43.3 C), set on July 5, 1918.
  • Further west, temperatures remained slightly below normal throughout July. Southern California saw a smattering of record lows during the last week of the month. The typical summer marine layer affected the California coast throughout the month; the airports at Los Angeles, Santa Barbara, and Monterey all reported 19 days with fog. To the north, Alaska experienced a cool and drizzly July. Average temperature for the month at Anchorage was 55.5 F (13 C), the second lowest July average on a record dating back to 1952.
  • July 14. Montana. Great Falls reported the highest atmospheric water vapor content this location has recorded in all of its weather balloon ascents in a record extending from 1948.
  • July (all month) Fires throughout the West: Severe fire weather continued for much of the West. These conditions coupled with with numerous thunderstorms this month led to numerous small wildfires and several large fires, described below. The number of fires in the US year-to-date is only 77% of the 10-year average, while the country is at 96% of average in acreage burned.
  • Oregon: The Long Draw Fire (north of McDermitt, Nevada) and Miller Homestead Fire (1/2 mi, 0.8 km west of Frenchglen, Oregon) both ignited due to lightning on July 8. The Long Draw fire burned 557,648 acres (225,672 hectares) before containment on July 15, by far the largest fire in Oregon’s history. The nearby Miller Homestead fire consumed 160,853 acres (65,094 hectares) before it was contained on July 24. In the past 15 years, 7 of the 11 westernmost states have recorded their largest fire since settlement.
  • Wyoming: The Arapaho Fire, 28 miles (45 km) northwest of Wheatland, Wyoming, ignited June 27 due to lightning. The fire continued throughout the month of July and at month’s end is 88% contained and burned 98,115 acres (39,705 hectares). July 31.
  • 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:


July 2012 Selected Climate Anomalies and Events MapJuly 2012 Selected Climate
Anomalies and Events Map

Global Highlights

  • The average combined global land and ocean surface temperature for July 2012 was 0.62°C (1.12°F) above the 20th century average of 15.8°C (60.4°F). This is the fourth warmest July since records began in 1880.

  • The globally-averaged land surface temperature for July 2012 was the third warmest July on record, at 0.92°C (1.66°F) above average.

  • The Northern Hemisphere land surface temperature for July 2012 was the all-time warmest July on record, at 1.19°C (2.14°F) above average.

  • ENSO-neutral conditions continued in the eastern equatorial Pacific Ocean during July 2012 as sea surface temperature anomalies in that region continued to rise. The average July worldwide ocean surface temperature ranked as the seventh warmest July on record.

  • The combined global land and ocean average surface temperature for January–July 2012 was the 10th warmest such period on record, at 0.53°C (0.95°F) above the 20th century average.


==global-temps-errata==

Please Note: The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. Effective with the July 2010 State of the Climate Report, NCDC transitioned to the new version (version 3b) of the extended reconstructed sea surface temperature (ERSST) dataset. ERSST.v3b is an improved extended SST reconstruction over version 2. For more information about the differences between ERSST.v3b and ERSST.v2 and to access the most current data, please visit NCDC's Global Surface Temperature Anomalies page.


Introduction

Temperature anomalies for July 2012 are shown on the dot maps below. The dot maps on the left provide a spatial representation of anomalies calculated from the Global Historical Climatology Network (GHCN) dataset of land surface stations using a 1961–1990 base period. The dot maps on the right are a product of a merged land surface and sea surface temperature (SST) anomaly analysis developed by Smith et al. (2008). For the merged land surface and SST analysis, temperature anomalies with respect to the 1971–2000 average 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.

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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 July 2012 height and anomaly mapJuly 2012 map—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.

July

The average global temperature across land and oceans during July 2012 was 0.62°C (1.12°F) above the 20th century average of 15.8°C (60.4°F) and ranked as the fourth warmest July since records began in 1880. The previous three months—April, May, and June—also ranked among the top five warmest for their respective months. July 2012 marks the 36th consecutive July and 329th consecutive month with a global temperature above the 20th century average. The last below-average July temperature was July 1976 and the last below-average temperature for any month was February 1985. It was the second warmest July in the Northern Hemisphere, behind only the record warmth of 2010. The Southern Hemisphere had its 13th warmest July on record.

The globally averaged temperature over land areas was the third highest for July on record. Notably, it was the warmest July on record for the Northern Hemisphere, where the majority of Earth's land mass is located. This is the fourth month in a row that the Northern Hemisphere has set a new monthly land temperature record. The Southern Hemisphere land temperature was also above average for July, but not as extreme, ranking 33rd in the 133-year period of record.

  • The average temperature for the contiguous United States during July was 1.8°C (3.3°F) above the 20th century average, marking the warmest July and all-time warmest month since national records began in 1895, surpassing the previous record warmth of July 1936.

  • Some of the greatest anomalous warmth in Canada was observed in the country's southern province of Ontario, particularly in northwestern Ontario and the Far North where record-breaking monthly temperatures occurred, according to Environment Canada. Throughout the province, the average July temperature was as much as 3.5°C (6.3°F) above average.

  • Norway as a whole was 0.3°C (0.5°F) cooler than average for the month of July. This marks the country's 30th coolest July since national records began in 1900. The coolest anomalies of -1.0 to -1.5°C (-1.8 to -2.7°F) were observed in the northern regions.

  • It was also cooler than average in the United Kingdom, where the July 2012 temperature anomaly was 1.0°C (1.8°F) below the long-term average. This was the coolest July since 2000.

  • While the area-averaged monthly maximum temperature for Australia was close to normal, the monthly average minimum temperature was the coolest July in the past 30 years and the eighth coolest July in the country's 63-year period of record, at 0.96°C (1.73°F) below average. The state of Western Australia reported its lowest average July minimum temperature on record—1.71°C (3.08°F) below average.

Across the world's oceans, the July average global sea surface temperature was 0.50°C (0.90°F) above the 20th century average of 16.4°C (61.5°F), making this the seventh warmest July on record. Ocean temperatures were notably below average in the northeastern Pacific Ocean and much higher than average in the northeast Atlantic and in the Labrador Sea near Greenland. This was also the highest monthly global ocean temperature anomaly since July 2010, a month that marked the onset of La Niña conditions that generally persisted until April 2012. During July, sea surface temperature anomalies continued to increase in the eastern and equatorial Pacific Ocean, the region where ENSO conditions are monitored. According to NOAA's Climate Prediction Center, El Niño conditions will likely develop by September 2012.

July Anomaly Rank
(out of 133 years)
Records
°C °F Year(s) °C °F
Global
Land +0.92 ± 0.13 +1.66 ± 0.23 Warmest 3rd 1998 +1.06 +1.91
Coolest 131st 1884 -0.57 -1.03
Ties: 2002
Ocean +0.50 ± 0.04 +0.90 ± 0.07 Warmest 7th 2009 +0.59 +1.06
Coolest 127th 1911 -0.49 -0.88
Ties: 2006
Land and Ocean +0.62 ± 0.09 +1.12 ± 0.16 Warmest 4th 1998 +0.71 +1.28
Coolest 130th 1911 -0.43 -0.77
Northern Hemisphere
Land +1.19 ± 0.14 +2.14 ± 0.25 Warmest 1st 2012 +1.19 +2.14
Coolest 133rd 1884 -0.60 -1.08
Ocean +0.54 ± 0.04 +0.97 ± 0.07 Warmest 7th 2005 +0.65 +1.17
Coolest 127th 1910, 1913 -0.54 -0.97
Land and Ocean +0.79 ± 0.12 +1.42 ± 0.22 Warmest 2nd 2010 +0.80 +1.44
Coolest 132nd 1913 -0.50 -0.90
Southern Hemisphere
Land +0.22 ± 0.11 +0.40 ± 0.20 Warmest 33rd 1998 +0.99 +1.78
Coolest 101st 1925 -0.68 -1.22
Ocean +0.48 ± 0.04 +0.86 ± 0.07 Warmest 7th 1998 +0.60 +1.08
Coolest 127th 1911 -0.48 -0.86
Ties: 2006
Land and Ocean +0.44 ± 0.06 +0.79 ± 0.11 Warmest 13th 1998 +0.67 +1.21
Coolest 121st 1911 -0.47 -0.85
Ties: 1991, 1995
Year-to-date (January–July)

Since February, the year-to-date global temperature anomalies for 2012 have increased each month as the year has progressed and La Niña conditions began to transition to the warmer El Niño phase — January: +0.36°C (+0.65°F); January–February: +0.36°C (+0.67°F); January–March: +0.39°C (+0.70°F); January–April: +0.46°C (+0.83°F); January–May: +0.49°C (+0.90°F), January–June: +0.52°C (+0.94°F), and January–July: +0.53°C (+0.95°F). The record for the warmest January–July was set in 2010, with a temperature that was 0.69°C (1.24°F) above average.

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

The January–July average worldwide land surface temperature was 0.88°C (1.58°F ) above the 20th century average, marking the sixth warmest such period on record. The warmth was most striking over central northern Russia and much of Canada and the contiguous United States. The U.S. reported its all-time warmest January–July on record. The coolest anomalies were observed over Australia and Alaska, where Alaska had its 15th coolest January–July since records began in that state in 1918.

The global ocean surface temperature for the year to date was 0.40°C (0.72°F) above average and tied with 2011 as the 11th warmest such period on record.

January–July Anomaly Rank
(out of 133 years)
Records
°C °F Year(s) °C °F
Global
Land +0.88 ± 0.21 +1.58 ± 0.38 Warmest 6th 2007 +1.12 +2.02
Coolest 128th 1893 -0.76 -1.37
Ocean +0.40 ± 0.04 +0.72 ± 0.07 Warmest 11th 1998 +0.57 +1.03
Coolest 123rd 1911 -0.51 -0.92
Ties: 2011
Land and Ocean +0.53 ± 0.09 +0.95 ± 0.16 Warmest 10th 2010 +0.69 +1.24
Coolest 124th 1911 -0.49 -0.88
Ties: 2001
Northern Hemisphere
Land +1.05 ± 0.26 +1.89 ± 0.47 Warmest 4th 2007 +1.29 +2.32
Coolest 130th 1893 -0.86 -1.55
Ocean +0.40 ± 0.05 +0.72 ± 0.09 Warmest 9th 2010 +0.56 +1.01
Coolest 125th 1910 -0.49 -0.88
Ties: 2001, 2006
Land and Ocean +0.65 ± 0.14 +1.17 ± 0.25 Warmest 6th 2010 +0.79 +1.42
Coolest 128th 1893 -0.54 -0.97
Southern Hemisphere
Land +0.42 ± 0.15 +0.76 ± 0.27 Warmest 22nd 2005 +0.93 +1.67
Coolest 112nd 1917 -0.76 -1.37
Ties: 1980
Ocean +0.42 ± 0.04 +0.76 ± 0.07 Warmest 12th 1998 +0.60 +1.08
Coolest 122nd 1911 -0.53 -0.95
Land and Ocean +0.42 ± 0.07 +0.76 ± 0.13 Warmest 13th 1998 +0.65 +1.17
Coolest 121st 1911 -0.54 -0.97
Ties: 1991, 1999

The most current data July 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 July 2012 varied significantly around the world.

  • July was drier than normal for Australia, with precipitation measured at 83 percent of average. However, the amount of precipitation was mixed across the country. Western Australia reported rainfall that was just 29 percent of average, the third driest July in the state's 113-year period of record, while Queensland in northeastern Australia saw rainfall that was 183 percent of its monthly average.

  • Parts of eastern central Argentina reported their driest July in more than 50 years, including the towns of Laboulaye, Pehuajó, and Dolores.

  • According to ZAMG, parts of Austria, mainly in the south and east, received unusually heavy downpours during July, with 18 stations across 5 states breaking monthly records (the period of record varies by station). The country's capital city of Vienna saw rainfall that was more than 250 percent of its monthly average.

  • In India, the southwest monsoon season that began in early June brought deficient rainfall to much of the country. According to the India Meteorological Department, July rainfall across the country was 87 percent of average. From June 1st through August 1st, seasonal rainfall was just 81 percent of the long term average. About 44 percent of the country observed average to above-average precipitation, while 56 percent reported deficits. Regionally, northwest India reported rainfall that was just 65 percent of average, while east and northeast India was 89 percent of average. In India, monsoon rainfall less than 90 percent of average constitutes drought.

  • According to the Japan Meteorological Agency, record 24-hour rainfall of up to 500 mm (20 inches) was observed on Japan's southern island of Kyushu in mid-July. Subsequent flooding and landslides killed more than two dozen residents.

Additional details on flooding and drought events around the world can also be found on the July 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 09 Aug 2012


July 2012Wildfires ravaged parts of Spain and Siberia's boreal forests. read more July 2012Heatstroke deaths spiked in Japan read more July 2012Cold snap triggered fatalities in Chile. read more July 2012Rains inundated U.K., Black Sea, and regions of India. read more July 2012Deadly flooding soaked East Asia. read more July 2012Severe storms pummeled eastern U.S. read more July 2012Tropical storms battered Korean Peninsula. read more July 2012Unprecendented ice melt observed in Greenland. read more July 2012Mosquitoes multiplied while corals decreased. read more



Drought conditions

Aerial View of Spain's Catalonia Burn Scar on 24 July 2012
Aerial View of Spain's Catalonia
Burn Scar on 24 July 2012
Source: NASA

Wildfires in northeastern Spain claimed four lives and injured 47 persons during late July—tragically denoting 2012 as the worst year for forest fires in that country in over a decade, according to media reports. Two wildfires raged in Catalonia bolstered by a Tramuntana (a strong, dry wind from the northwest). The fire near the city of La Jonquera consumed 32,000 acres and forced the closure of major roads and rail services into France, while another fire near the coastal city of Portbou burned over 22,000 acres. At least 135,000 residents were advised to stay indoors and 800 children were evacuated from camps across the Alt Emporda region while about 4,200 homes lost utilities. A combined force of 950 Spanish and French firefighters supported by 350 soldiers, police, and volunteers, as well as 33 aircraft, brought the flames under control. A third fire blazed in southwestern Spain, which led to an evacuation of 50 people in Cambron. Having experienced its driest winter in 70 years, persistent drought conditions in Spain have resulted in high risk of wildfires during this summer. Earlier wildfires in Spain's Canary Islands (an archipelago near the western coast of Africa) forced evacuations of 90 people in Tenerife, 60 people in La Gomera, and 160 people in La Palma at mid-month. One of the fires scorched parts of Spain's largest national park Teide—designated United Nations Education, Scientific and Cultural Organization (UNESCO) World Heritage site, when at least 4,500 acres were burned on Tenerife; also 17 acres burned on La Gomera (an UNESCO biosphere reserve); and 990 acres burned on La Palma. Nearly 1,100 firefighters supported by 20 helicopters and firefighting planes battled the island blazes.


Madeira Islands Smoke Plumes on 19 July 2012
Madeira Islands Smoke Plumes
on 19 July 2012
Source: NASA Earth Observatory

Wildfires occurred elsewhere across southern Europe in July, according to media reports. Mainland Portugal and its Madeira Islands were hit by intense wildfires, forcing dozens to flee their homes. Over 1,000 firefighters battled numerous major wildfires in northern and central Portugal. One firefighter died and seven others were injured, at least five homes were lost, and more than 12,000 acres were consumed.

In Greece, nearly 80 wildfires swept through the country at mid-month. Officials declared a state of emergency in Patras when that city became surrounded on three sides by wildfires, which were exacerbated by strong winds and soaring temperatures. Hundreds of its residents and university students were forced to evacuate as smoke filled the air of Greece's third-largest city. Near Athens, two persons were injured, several homes were damaged, and over 300 people were evacuated from summer camps, a retirement home, and a monastery, according to media accounts.

In Croatia, one firefighter perished and 1,500 tourists were evacuated along the Adriatic coast where the main highway was closed due to heavy smoke.

In Macedonia (Former Yugoslav Republic of Macedonia), two people died and 14 others were injured in a 50-acre forest fire at Strumica on July 24th, according to media accounts.


Smoke Plumes from Siberian Wildfires on 09 July 2012
Smoke Plumes from Siberian
Wildfires on 09 July 2012
Source: NASA Earth Observatory

Massive wildfires continued to rage in central and eastern Siberian. As of July 9th, rapidly spreading blazes increased the size of the burn area to nearly 61,000 acres and involved up to 2,000 personnel and 200 vehicles in firefighting efforts, according to media reports. From January through July 2012, more than 1,800 taiga wildfires have burned close to 485,000 Russian acres, and eight paratroopers died combating those flames in June. Smoke from the Russian fires reached North America during mid-May, while creating spectacular sunsets over Alaska, contributed to air quality issues in the Northwest U.S. by early July. On July 8th–9th, the smoke caused record-high levels of ozone in British Columbia—nearly three times the average for July, according to media reports.

In the U.S., four firefighters—members of the North Carolina National Guard, were killed in air tanker crash on July 1st. The team was part of a fleet battling the 9,000-acre White Draw wildfire in South Dakota. The Long Draw wildfire consumed over 560,000 acres in southeast Oregon, thus becoming that state's biggest blaze since 1865. A second fire, Miller Homestead, scorched an additional 160,000 acres in Oregon where multiple fires have adversely impacted the region's cattle-farming industry.

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Extreme Temperatures

Around the Northern Hemisphere, high temperatures turned deadly. Up to 39 heatstroke deaths occurred in Japan during July as the oppressive heat forced over 21,000 residents to seek medical attention, according to media accounts. Japan's daytime temperatures hit 35°C (95.0°F) or above for ten consecutive days during the month. Elsewhere, the unprecedented heat wave throughout the central U.S. had contributed to 74 deaths by mid-month. Numerous U.S. cities experienced multiple days of triple-digit temperatures during July. July 2012 was the hottest July and hottest month in U.S. records dating to 1895. Please visit NOAA's National Overview page for additional information.

In the Southern Hemisphere, low temperatures plunged at locations in South America and Australia. According to media reports, 16 deaths resulted from a cold snap in central Chile over the first weekend of July when nighttime temperatures dipped to -8°C (17.6°F). As the cold moved eastward, below-normal temperatures coupled with frost hampered wheat-planting efforts by Argentinean farmers. In Australia, Alice Springs recorded its coldest mean July minimum temperature in 35 years with a value of -0.3°C (31.4°F) as 19 days of the month fell below freezing. The continuous cold resulted in numerous occurrences of broken water pipes for residents. Likewise, Perth set an all-time low mean July minimum temperature with a value of 5.2°C (41.4°F), where sunshine averaged only 7.4 hours per day, according to media reports.

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Heavy rainfall and flooding

In the United Kingdom (U.K.), deluges of precipitation drenched areas from southwest England to the Scottish Lowlands—with some parts receiving up to half or more of a year's worth of rain within hours. The UK's average rainfall for July is 69.9 mm (2.75 inches). The region's extreme weather has been attributed to the position of the overhead Jet Stream being farther to the south than is usual for summer. When this fast-moving, narrow band of air (at six to seven miles above the Earth's surface) lies to the north of the U.K., the winds and rain are steered towards Iceland and Scandinavia. According to media accounts, Devon received 35 mm (1.38 inches) and Holbeach Lincolnshire received 36 mm (1.42 inches) during a six-hour period on July 6th and flash floods resulted. In Devon, the 24-hour total of rainfall was 56.6 mm (2.23 inches). One death was reported; the Red Cross assisted with evacuations of residents; at least 100 properties were flooded; roadways and rail services closures caused travel delays. Adverse economic impacts arose when nearly 30,000 spectators of the British Grand Prix were advised to forego part of the multi-day event and the Great Yorkshire Show—a major British agricultural fair with estimated revenues approaching $3.5 million U.S. dollars was canceled.

Flooding in northeastern India has resulted from exceptionally heavy and continuous monsoon rains which began during June, and was deemed the worst in 30 years, according to media reports. Within the Indian state of Assam the humanitarian impacts were severe with at least 117 people having died, millions of people made homeless, and tens of thousands of people being without safe drinking water.


Storm Produced Flash Floods in Russia on 06 July 2012
Storm Produced Flash Floods
in Russia on 06 July 2012
Source: NOAA Visualization Lab

Torrential rains sweeping through southern Russia the first week of July resulted in over 140 deaths (from drowning and electrocution), at least 5,000 homes being flooded, and thousands of people were evacuated. Media accounts depicted the devastation in the city of Krymsk as the worst seen in 70 years when 279.4 mm (11 inches)—an average two months' worth—of rain fell within a few hours on July 6th. Oil shipments were suspended from the city of Novorossiysk, which is the country's main port on the Black Sea.

Japan Rainfall Totals near Aso for July 6–12, 2012
Japan Rainfall Totals near Aso
for July 6–12, 2012
Source: NASA Earth Observatory


China Rainfall Totals near Beijing for July 21–22, 2012
China Rainfall Totals near Beijing
for July 21–22, 2012
Source: NASA Earth Observatory

Intense rains on July 14th–15th with hourly rainfall rates in excess of 90 mm (3.5 inches), caused flash flooding and landslides in southern and western Japan—where areas already hard-hit by flooding received another 800 mm (31.5 inches). According to media reports, there were 28 deaths, 250,000 residents were evacuated, and over 4,300 properties were damaged as well as notable agricultural losses of rice paddies. Japanese troops airlifted supplies to thousands of people trapped in mountainous districts as 800 roads and 20 bridges were closed. Up to an additional 152 mm (6 inches) of rain was deposited over Japan by passage of a tropical storm system on July 19th.

As much as 170 mm (6.7 inches) of precipitation fell within 16 hours in regions near China's capital city on July 21st and caused flooding considered as the worst in six decades, according to media reports. At least 77 people died, while nearly 700,000 Beijing residents were evacuated and 80,000 travelers were stranded when 500 airline flights were canceled. Torrential rains later in the month—197 mm (7.8 inches) in 3 hours—in areas southwest of Beijing resulted in 18 deaths.

A deluge on July 29th dumped 400 mm (15.7 inches) of rain in 24 hours from thunderstorms over North Korea, exacerbating already saturated conditions created by Tropical Storm Khanun around mid-month. Media reported that widespread flooding in the country resulted in 88 deaths with 134 people injured during July, and left nearly 63,000 residents homeless and over 75,000 acres of farmland in ruins.

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Severe Storms

U.S. Storm Reports for 26 July 2012
U.S. Storm Reports
for 26 July 2012
Source: NOAA Storm Prediction Center

A violent storm ripped through the eastern U.S. in early July claimed four lives and injured six people, while thousands of downed trees in the Great Smoky Mountains National Park forced the closure of its roads and trails. Two deaths occurred when lightning struck on July 24th in southwestern Pennsylvania where a family was picking blackberries. More severe thunderstorms—which produced multiple tornadoes and quarter-sized hail, rolled across the country's Midwest and Northeast regions on July 26th causing loss of power to nearly 300,000 residents and 900 airline flights to be canceled. According to media reports, the powerful storms resulted in three deaths in New York.

The U.S. also experienced a near record-low number of tornadoes—the fewest for a July since the 1950s. Historical U.S. records indicate that 23 tornadoes occurred in July 1950 and 1951. At 24 tornadoes, the preliminary count for the month in the U.S. was a notable drop from the previous near record-low of 42 twisters set in July 1960, according to media reports. The climatological factors contributing to the country's intense drought impeded the development of the severe storms which tend to produce tornadoes. Please visit NOAA's Tornadoes page for additional information.

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Tropical Cyclones

Eastern Pacific Hurricanes on 13 July 2012
Eastern Pacific
Hurricanes on 13 July 2012
Source: NASA

Three tropical cyclones formed in the Eastern Pacific during July—all attained hurricane strength, but none posed a threat to land areas. Specific statistics for Hurricanes Daniel, Emilia, and Fabio can be found at NOAA's Hurricanes & Tropical Storms page. A concise synopsis is also available at NASA's Hurricanes/Tropical Cyclones page.

Tropical cyclones were active in the Western Pacific with four named storms forming during the month. Tropical Storm Khanun (a.k.a. Enteng; July 14th–19th) originated northwest of Guam and moved across the East China Sea to render deadly flooding in the Korean Peninsula.

Typhoon Vicente (a.k.a. Ferdie; July 18th–July 26th) passed over the Philippines causing adverse conditions before reaching southern China. According to media reports, two persons died and 1,140 people were evacuated in the northern Philippines amid numerous incidents of flooding and tornado damage as the storm amplified adverse conditions being caused by the Southwest Monsoon. Major disruption occurred within the city of Hong Kong as strong winds and rain forced closure of the financial markets, caused delays in transportation services, and inflicted injuries to at least 118 people.


Western Pacific Hurricanes on 01 August 2012
Western Pacific
Hurricanes on 01 August 2012
Source: NASA

Typhoon Saola (a.k.a. Gener; July 26th–Aug 2st) formed east of the Philippines and slowly advanced northwest to hit the Taiwan coast, before reaching China's Fujian province. According to media reports, Saola produced massive flooding in the Philippines which resulted in 39 deaths, forced evacuation of at least 230,000 people, and loss of utilities for over two million residents. In Taiwan, where nearly 900 mm (35 inches) of rain fell by August 1st, at least five storm-related deaths were known, heavy winds disrupted rail and airline travel, and many highways were closed due to flooding and mudslides. In China, nearly 60,000 fisherman and maritime workers were evacuated and shipping routes were closed, as officials issued the first 2012 "red-alert" warning—the highest of that country's four-tier system. Tropical Storm Damrey (July 28th–Aug 2nd) followed a path along Japan to also make landfall along eastern China, only hours before Saola. The compact tropical storm punched southern Japan with torrential rains and violent winds, where rain fall had an estimated intensity rate of 80 mm (3.2 inches) per hour, and kept hundreds of airline flights grounded, according to media reports. In China, two deaths and 29 injuries resulted as Damrey dumped 174 mm (6.8 inches) of precipitation. As many as 306,000 residents of Fujian and at least 461,000 residents of Zhejiang, Jaingsu, and Shandong provinces were evacuated due to the storms.

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Polar Events and Sea Ice
Greenland Thawing Analysis from July 8–12, 2012
Greenland Thawing Analysis
from July 8–12, 2012
Source: NASA

Petermann Glacier Calving Arial view on 17 July 2012
Petermann Glacier Calving
Arial view on 17 July 2012
Source: NASA Earth Observatory

Phenomenal melting of Greenland's ice sheet was identified by NASA and university scientists during July. High pressure aloft anchored above the island induced warm and clear weather conditions that contributed to the rapid thawing, according to media accounts. The ice melt area which expanded from 40 percent to nearly 97 percent within 4 days was unusual in terms of speed and extent—exceeding the maximum thawing observed by satellite in three decades (previously about 55 percent) for Greenland. Ice cores indicated that large-scale melting occurs on average about once every 150 years with 1889 being the last event.

In northwestern Greenland, a massive iceberg broke away from Petermann's Glacier along a rift existing since at least 2001. At 32.3 square kilometers (12.5 square miles), this iceberg was roughly half the size of one which calved in July 2010 and deemed to be associated with ocean currents rather than the surface melt. In southwestern Greenland, a group of sightseers cruising the waters of the Ilulissat Icefjord—an UNESCO World Heritage Site, witnessed a thunderous iceberg split firsthand and although shaken by the resulting "ice wave" were fortunately unharmed. Elsewhere, melt runoff produced flooding of the Watson River and damaged a bridge which provided access to one of the island's major commercial airports.

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Ecosystems Impacts

Research of climate factors which influence tropical diseases garnered resources from the World Health Organization in July. In partnership with Canada's International Development Research Center, a major program (valued at $6.8 million U.S. dollars) was implemented to understand the impact of climate change in sub-Saharan Africa on people's susceptibility to diseases carried by mosquitoes, flies, and snails.

Warm temperatures coupled with stagnant waters lingering in flooded areas on two continents yielded favorable conditions as breeding ground for mosquitoes. According to media reports, 2,000 cases of Dengue Fever with 23 deaths occurred in the Philippines between January and July 2012 and reflected an increase of 16 percent compared to the same period of 2011. As of July 31st,the U.S. Center for Disease Control and Prevention had received reports of 241 cases of the West Nile virus—the highest number since 2004 within the nation, and four deaths were known to have occurred. In Minnesota, where the city of Minneapolis conducts one of the world's largest mosquito-abatement programs using a budget of $17 million U.S. dollars to treat between 175,000 and 225,000 acres of wetlands annually, officials accelerated control measures during July, according to media reports. Two-hundred thousand acres have been treated with a granular material which results in death to the mosquito larvae ingesting it.

Whereas in U.S. areas afflicted by lack of water, entomologists noted increases in other pests. Hot, dry conditions impede the natural bacteria and fungi which tend to control insects like grasshoppers and crickets that can potentially devastate crops such as alfalfa and tobacco.

Dust Plume crossing Atlantic Ocean on 21 July, 2012
Dust Plume crossing Atlantic Ocean
on 21 July, 2012
Source: NASA Earth Observatory

Dust Plume crossing Red Sea on 26 July 2012
Dust Plume crossing Red Sea
on 26 July 2012
Source: NASA Earth Observatory

Dust Plumes over Argentina on 29 July 2012
Dust Plumes over Argentina
on 29 July 2012
Source: NASA Earth Observatory

Dust from Africa's Sahara Desert was observed to be traversing eastward across the Atlantic Ocean and reached the Florida coast during July. Evidence suggests that heavy dust transport has coincided with Caribbean coral declines in the past. Meanwhile, dry riverbed sediments from the Africa's Sudan desert blew western over the Red Sea during the following week. Dust plumes ascended over Argentina as a result of persistent dry conditions around its lake, Laguna Mar Chiquita.

During the International Coral Reef Symposium held mid-month in Cairns, Australian, scientists urged for actions to preserve the coral reefs. Rising ocean temperatures have significantly inflicted damage to corals across the world. Overfishing and influxes of sediment and pollution were cited as contributing factors. Likewise, another study released in July concluded that greenhouse gas emissions amplify effects of climate change's influence on the collapse of coral reefs in the eastern Pacific, according to media reports. Deforestation occurring in Madagascar was cited within another study as adversely impacting corals in the western Indian Ocean due to resulting soil erosion.

At least 60 wild peacocks perished in Pakistan's Thar desert during July. While no conclusive causes were known, the birds were likely weakened by multiple factors linked to the delay of the annual monsoon rains, according to media reports.

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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

Upper-level circulation pattern and anomalies averaged for July 2012
Upper-level circulation pattern and anomalies averaged for July 2012.

The weather patternweather pattern over North America in July 2012 was dominated by subtropical high pressure (High, or upper-level ridge) associated with the Bermuda High. Cool fronts occasionally penetrated the High, but the main storm track stayed far to the north. Although the cool fronts triggered areas of thundershowers and locally heavy rainfall, mainly along the periphery of the High, descending air ("subsidence") associated with the High played the dominant role in this month's weather — generally inhibiting precipitation from the cool fronts and stopping the formation of most convective showers that are normally triggered by afternoon heating from the sun. The subsidence also contributed to much above-normal temperatures and a near-record low tornado count this month. The High's abnormal dryness and blistering heat brought about a continued expansion of drought across the country, especially from the Great Plains to the Ohio Valley, with devastating impact on crops and livestock. An active summer monsoon season brought above-normal rainfall to parts of the Southwest, but the West (and some areas east of the Rockies) was plagued by numerous large wildfires which resulted in the fourth largest wildfire month for July, nationally, in terms of acres burned.

The dominance of the High can be seen in the persistence of above-normal temperatures across much of the country, and below-normal precipitation in the central regions, in the weekly temperature (weeks 1, 2, 3, 4) and precipitation (weeks 1, 2, 3, 4) anomaly maps. The result of below-normal supply (precipitation) and above-normal demand (evapotranspiration due to above-normal temperatures) in the drought equation was an expanding area of severely dry drought conditions as measured by the weekly Palmer Crop Moisture Index (weeks 1, 2, 3, 4). By the time the month was over, July 2012 ended up with a rank of warmest and 28th driest July, nationally, in the 1895-2012 record.

Nearly seven times as many record warm highs and lows occurred than record cold highs and lows. About 4400 daily high temperature records and over 3600 record warm daily low temperatures were tied or broken. In comparison, about 320 record low temperatures and 880 record cool daily high temperatures were tied or broken. (These numbers are preliminary and are expected to increase as more data arrive.) On a statewide basis, 32 states had the tenth warmest, or warmer, July in the 118-year record, with Virginia ranking warmest on record. The unusual warmth occurred across the country and contributed to the third largest national Residential Energy Demand Temperature Index (REDTI) for July.

Above-normal precipitation fell along the eastern periphery of the High — from the western Gulf coast to the central Appalachians — where Gulf of Mexico moisture was entrained along cool fronts. Parts of the Southwest were wetter than normal where summer monsoon showers occurred along the western edge of the High. But the weather was predominantly dry beneath the core of the High. Four states (Nebraska [second driest], Iowa [third], Illinois [fourth], and Missouri [ninth]) had the tenth driest, or drier, July in the 1895-2012 record, with Kansas ranking twelfth driest. Maine also ranked in the top ten driest category. On the other hand, three states (California, Nevada, and West Virginia) ranked in the top ten wettest category. The combination of abnormally dry conditions and high evapotranspiration due to excessive heat resulted in an extensive area of severe to extreme short-term drought. Consequently, long-term drought conditions intensified in the Great Plains and Midwest and expanded nationwide (U.S. Drought Monitor for July 31st versus July 3rd, Palmer Drought Severity Index for July versus June). According to the July 31st U.S. Drought Monitor, moderate to exceptional drought grew to cover 63 percent of the contiguous United States, an increase of 7 percent compared to last month. However, the percent area of the country in the worst drought categories (extreme to exceptional drought) doubled, from 10 percent last month to 22 percent this month. According to the Palmer Drought Severity Index, whose record spans the 20th century, about 57 percent of the contiguous U.S. was experiencing moderate to extreme drought. The last time drought was this extensive was in December 1956 when about 58 percent was in moderate to extreme drought.

When averaged together, the mixture of temperature and precipitation extremes gave the U.S. (as noted above) the warmest and 28th driest July in the 118-year record. Averaging extremes tends to cancel them out. But when extremes are combined cumulatively, like in the U.S. Climate Extremes Index (CEI), they may tell a different story. The large spatial extent of unusually warm highs (largest), unusually warm lows (largest), very dry conditions (third largest), and extreme one-day precipitation (eighth largest) gave the U.S. its largest CEI for July, barely surpassing July 2011. All of the regions except the Northwest and West had July regional CEI values in the top ten category. The combination of persistent and unusual warmth and drought over the last several months have contributed to the highest national CEI for the last six months (February-July) and year-to-date (January-July), second highest for the last 12 months (August-July), and fourth highest for the last three months (May-July).

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 July:

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.

The upper-level circulation anomalies for both July 2012 and May-July 2012 over the northeast Pacific and downstream over North America are generally consistent with the EP-NP pattern. The above-normal heights over the central U.S. are shifted north reflecting a stronger High, with an upper-level trough over western North America coinciding with below-normal sea surface temperatures in the northeastern North Pacific and along the west coast of North America. The pattern of observed temperature anomalies for July 2012 and the last three months (May-July) corresponds to the negative phase of the EP-NP across most of the country. The July 2012 and May-July precipitation patterns also correspond weakly to a negative EP-NP index where the correlations exist. The precipitation pattern also suggests some hint of the positive and negative phases of the AO and PNA fighting to influence our weather. 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.

Updated: 8 August 2012

The values in this report are preliminary, and the final counts and results will change as tornado events are investigated and confirmed. This month’s report will not be updated with final statistics. For final information please visit the following sites:



According to data from the Storm Prediction Center, during July, there were only 24 preliminary tornado reports. This is the least number of tornadoes reported during the month since 23 tornadoes occurred in July 1950 and July 1951. It is possible the number will be revised lower once storm surveys are completed. On average, the U.S. experiences 134 tornadoes during July. This also marks the least active tornado month since January 2011, when 16 tornadoes were confirmed. The weather pattern during the month that contributed to the low tornado count was also associated with the worsening drought conditions that impacted over 60 percent of the country.

On July 28th, a tornado touched down along the northeastern slope of Mount Evans in Colorado at an elevation of approximately 11,900 feet above sea level. The location was remote and no structural damage or injuries were reported. The tornado was uncommon due to the high elevation of its occurrence, marking the second highest elevation at which a tornado has been observed in the nation. Mountainous terrain and high elevations typically create unfavorable conditions for tornadoes, making these events rare, but not impossible. The highest elevation of an observed tornado in the country occurred in July 2004 at 12,000 feet above sea level in California’s Sequoia National Park.

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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.

East North Pacific Basin

Daniel
Tropical Storm Daniel Satellite Image
Daniel Track
Tropical Storm Daniel Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Daniel
Cyclogenesis Date 07/05
Cyclolysis Date 07/11
Highest Saffir-Simpson Category Cat 2
Maximum 6-hr Sustained Wind 109 mph (95 kt or 176 km/h)
Min Pressure 961 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 11.1050 x 104
Landfall Information (date, location and sustained winds)
Deaths
*The (ACE) Index calculations are based on preliminary data.

Emilia
Tropical Storm Emilia Satellite Image
Emilia Track
Tropical Storm Emilia Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Emilia
Cyclogenesis Date 07/08
Cyclolysis Date 07/15
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) 17.9850 x 104
Landfall Information (date, location and sustained winds)
Deaths
*The (ACE) Index calculations are based on preliminary data.

Fabio
Tropical Storm Fabio Satellite Image
Fabio Track
Tropical Storm Fabio Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Fabio
Cyclogenesis Date 07/12
Cyclolysis Date 07/17
Highest Saffir-Simpson Category Cat 2
Maximum 6-hr Sustained Wind 104 mph (90 kt or 167 km/h)
Min Pressure 972 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 10.0050 x 104
Landfall Information (date, location and sustained winds)
Deaths
*The (ACE) Index calculations are based on preliminary data.

West North Pacific Basin

Khanun
Tropical Storm Khanun Satellite Image
Khanun Track
Tropical Storm Khanun Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Khanun(Enteng)
Cyclogenesis Date 07/16
Cyclolysis Date 07/18
Highest Saffir-Simpson Category TS
Maximum 6-hr Sustained Wind 58 mph (50 kt or 93 km/h)
Min Pressure 985 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 1.9700 x 104
Landfall Information (date, location and sustained winds)
Deaths 89
*The (ACE) Index calculations are based on preliminary data.

Vicente
Tropical Storm Vicente Satellite Image
Vicente Track
Tropical Storm Vicente Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Vicente(Ferdie)
Cyclogenesis Date 07/21
Cyclolysis Date 07/25
Highest Saffir-Simpson Category Cat 4
Maximum 6-hr Sustained Wind 138 mph (120 kt or 222 km/h)
Min Pressure 950 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 6.4775 x 104
Landfall Information (date, location and sustained winds) 07/23 - Guangdong, China (120 kt or 222 km/h)
Deaths 22
*The (ACE) Index calculations are based on preliminary data.

Saola
Tropical Storm Saola Satellite Image
Saola Track
Tropical Storm Saola Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Saola(Gener)
Cyclogenesis Date 07/28
Cyclolysis Date 08/03
Highest Saffir-Simpson Category Cat 2
Maximum 6-hr Sustained Wind 104 mph (90 kt or 167 km/h)
Min Pressure 960 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 8.9600 x 104
Landfall Information (date, location and sustained winds) 08/01 - Taiwan (85 kt or 157 km/h)
Deaths 45
*The (ACE) Index calculations are based on preliminary data.

Damrey
Tropical Storm Damrey Satellite Image
Damrey Track
Tropical Storm Damrey Forecast Track


Safir Simpson Color Legend for Track Map from Unisys
Saffir-Simpson Scale Color Legend
Tropical Cyclone Summary
Tropical Cyclone Damrey
Cyclogenesis Date 07/29
Cyclolysis Date 08/03
Highest Saffir-Simpson Category Cat 1
Maximum 6-hr Sustained Wind 86 mph (75 kt or 139 km/h)
Min Pressure 970 mbar
Accumulated Cyclone Energy (ACE*) Index (kt2) 5.8100 x 104>
Landfall Information (date, location and sustained winds) 08/02 - Xiangshui County, China (65 kt or 120 km/h)
Deaths 4
*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 15 August 2012
Contents Of This Report:
Map showing Palmer Z Index

National Drought Overview

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Detailed Drought Discussion

Overview

July 2012 was another warmer- and drier-than-average month (warmest and 28th driest July on record, based on data back to 1895) when weather conditions are averaged across the country. A strong high pressure system (High, or upper-level ridge) kept its stranglehold over much of the U.S. for most of the month, resulting in persistent warm anomalies (weeks 1, 2, 3, 4) which dominated most of the country. Descending air ("subsidence") associated with the High inhibited precipitation in the central states, but a few cool fronts triggered areas of rain along the southern and eastern peripheries of the High, and monsoon showers brought rain to its western periphery (weeks 1, 2, 3, 4). The dry weather, in combination with increased evaporation caused by the record heat, expanded drought conditions in the West, Great Plains, and Midwest, while below-normal rainfall expanded drought conditions in Hawaii. Nationally, the moderate-to-exceptional (D1-D4) drought footprint increased to about 53 percent of the country while the percentage in the abnormally dry to exceptional drought category generally held steady at about 71 percent. About 19 percent of the country was in the worst drought categories (D3-D4, extreme to exceptional drought), more than double the percentage from last month. The Palmer Drought Index, whose data base goes back 113 years, is relied upon for drought comparisons before 2000. The July 2012 Palmer value of 57 percent is the largest percentage since December 1956 when 58 percent of the contiguous U.S. was in moderate to extreme drought.

The U.S. Drought Monitor drought map valid July 31, 2012
The U.S. Drought Monitor drought map valid July 31, 2012.

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

Historical Perspective

As noted in more detail in the Historical Analog section below, the droughts of the 1930s were largely a succession of expansions and contractions, characterized as "waves" of very intense drought spreading over huge expanses of the country, then retreating to a relatively small epicenter. The first huge drought expanded from the eastern U.S., but by the middle of the decade drought waves expanded from the Plains. These were the widely-known "Dust Bowl" days. The 1950s were much more persistent in their coverage. The 1950s drought dominated the early to middle decade, expanding and retreating (but more slowly) with the epicenter in the Southern Plains, particularly Texas and New Mexico, and into adjacent areas of Mexico. Much of the South and Gulf Coast was seriously involved in this drought regime. At its peak, most of the country was involved in the drought. Most drought was eradicated during a very wet 1957. The droughts of the 2000s were large, intense, regional events, and did not emanate from, or return to, the same regions in the way that the droughts of the 1930s and 1950s did. Compared to the "Drought Decades" of the 1930s and 1950s, the drought features were smaller in size and more migratory from one part of the country to another, but their intensity was strong. However, the western U.S. did see persistent drought during the first half of the decade.



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

In some respects, the dryness of July intensified the long-term dryness which had become evident in June. As seen on the July 2012 Palmer Z Index map, low precipitation and record hot temperatures (with the accompanying increased evapotranspiration) led to short-term drought across much of the central part of the country this month. Wet conditions are evident on the Z Index map along the periphery of the dry area — in parts of the Great Lakes, Appalachians, Gulf of Mexico coast, Southwest, and Pacific Northwest. The Palmer Z Index map also indicates July dryness in parts of the East Coast. Compared with the June 2012 PHDI map, the July 2012 PHDI map indicates that drought conditions deteriorated from the central Rockies to Ohio Valley and Great Lakes, but improved along parts of the Gulf of Mexico coast and in the Southwest. The July 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 Southwest and Deep South drought areas, and parts of New England dried out, but for much of the rest of the country — drier-than-normal weather persisted over the existing drought areas and wetter-than-normal weather continued over parts of the already-moist Pacific Northwest.


Palmer Drought Model Potential Evapotranspiration

July 2012 Precipitation minus Potential Evapotranspiration map
Precipitation minus Potential Evapotranspiration for July 2012 calculated using the Palmer Model.
April-July 2012 Precipitation minus Potential Evapotranspiration ma
Precipitation minus Potential Evapotranspiration for April-July 2012 calculated using the Palmer Model.

Did You Know?

Potential Evapotranspiration

The Palmer drought indices measure the balance between moisture demand and moisture supply. Drought results from an imbalance between these two components. Precipitation provides the water supply. Water demand is usually measured by evapotranspiration (the amount of water that would be evaporated and transpired by plants). There is a distinction made between potential evapotranspiration (PE) and actual evapotranspiration (AE). The Palmer model uses Thornthwaite's equations to estimate PE from temperature. PE is the demand or maximum amount of water that would be evapotranspired if enough water were available (from precipitation and soil moisture). AE is how much water actually is evapotranspired and is limited by the amount of water that is available. AE is always less than or equal to PE, so PE is used for the water demand component of the drought equation.

In the Palmer model, if the amount of precipitation (P) during the month is greater than PE for the month, then the leftover P soaks into the ground to recharge soil moisture, and any left over after that runs off as streamflow. If P is less than PE, then moisture has to be drawn out of the soil to meet the PE demand. Hotter temperatures result in greater PE which requires more P just to meet the greater demand. Climates where PE is always greater than P are termed arid climates. The American Southwest is a typical arid climate.

More about climate monitoring…

During July 2012, temperatures were much above normal across much of the country — from the Northern Rockies to the Northeast, across the Great Plains and into the Southeast — resulting in potential evapotranspiration (PE) values which exceeded five inches across most of the country, and seven inches across much of the Great Plains and Midwest agricultural belt. Precipitation (P) amounts were well below normalless than three inches from the heart of the Midwest to the West Coast — resulting in P minus PE values (water supply minus water demand values) which went strongly negative and further sapped soil moisture reserves, stressed crops and other vegetation, and shrank 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, soil moisture impacts) are the Rocky Mountain states, Central Plains, and Ohio Valley. Aside from the normally arid West, these areas have had the least precipitation and smallest percent of normal precipitation during the April-July growing season. With the unusual warmth of the last four months, PE during April-July has been excessive. The precipitation deficits and extra PE during this season have sent P minus PE values well into negative territory during the important growing season in America's agricultural heartland. If normal precipitation had fallen during this time, P minus PE values would still have been negative for these agricultural areas, but the stress on crops would have been far less.


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 3-month Standardized Precipitation Index 6-month Standardized Precipitation Index

The 1-month SPI shows the domination of high pressure over the central part of the country, with very dry conditions surrounded by wet conditions along its periphery (as described earlier). Dryness in northern New England and the southeast corner of the country is also evident at the one month timescale. The persistence of the High over the central U.S. for the past several months is reflected by dry conditions from the Great Plains to Midwest at 2 to 6 months, with dryness also spread into parts of the West. At 6 and 9 months, two core areas of dryness begin to manifest, one centered over the Ohio Valley and the other stretching from the Central Plains to Intermountain Basin, with pockets of dryness in the East. At 12 months there are two areas of dryness, one in the Southeast and the other stretching from the West Coast to Midwest. The pattern at 24 months is largely wet conditions along the northern tier states and dryness in the southern states. The ring of wetness along the edges of the country, which surrounds the central core dry area, is evident from 1 to 3 months. Wetness is observed in the Pacific Northwest throughout most of the time scales, in New England at 2 and 3 months, and across the Northeast at 12 and 24 months.


9-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:

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

Based on July 30th U.S. Department of Agriculture reports, 48 percent of the nation's corn crop was rated in poor to very poor condition. This is more than twice the 22 percent at the end of June. Thirty-seven percent of the national soybean crop was rated poor to very poor (compared to 22 percent a month ago), 42 percent of sorghum (24 percent last month), and 57 percent of the nation's pasture and rangeland (43 percent last month). In some states, nearly all of the pasture and rangeland was rated poor to very poor (Missouri at 98 percent, Illinois at 95 percent). The drought has taken a toll on the nation's soil moisture, with virtually all of the topsoil in the Great Plains to Midwest core drought area short or very short of moisture.

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

July 2012 was characterized by below-normal rainfall across much of the Hawaiian Islands. Abnormally dry to moderate drought conditions expanded into the northern islands this month, with moderate to extreme drought affecting about 54 percent of the state. Longer-term conditions continued drier than normal (last 2, 3, 4, 6, 12, 24, and 36 months, year-to-date, and water-year-to-date), especially for the southern islands.

In Alaska, July 2012 was generally drier than normal along a strip covering the central third of the state, wetter than normal along the west coast, and had a mixed pattern in the eastern sections. At short time scales (2, 3, 4, 6, and 7 months) relative dryness was significant in the north central sections, while at longer time scales a dry pattern at interior stations becomes evident (12, 24, and 36 months, and water-year-to-date). An area of abnormal dryness covered the northern areas on the USDM map.

Southern and eastern portions of Puerto Rico were drier than normal during July. These areas have been persistently drier than normal at longer time scales (2, 3 and 6 months, and year to date and water year to date). The July 31st USDM map had an area of abnormal 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-July, 1895-2012
Nebraska statewide precipitation, May-July, 1895-2012.

Over a tenth of the U.S. was very dry (the driest ten percent of the historical record) during July 2012. The national rank for July 2012 was the 28th driest July in the 118-year record. On a statewide basis, July 2012 ranked in the top ten driest Julys for five states — one of which was Maine, but four of them (Nebraska [second driest], Iowa [third], Illinois [fourth], and Missouri [ninth]) were in the Central Plains to Midwest agricultural belt under the influence of an upper-level high pressure ridge. Kansas, which ranked twelfth driest, was also affected by the ridge. Ten other states ranked in the driest third of the historical record.

The spatial pattern of dryness was larger at the three month time scale. Arkansas, Kansas, and Nebraska each had their driest May-July on record, with seven other states (from the Central Rockies to Ohio Valley) ranking in the top ten driest category. Eleven other states ranked in the driest third of the historical record.

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

Three centers of dryness appear at the six month time scale — the Southwest to Central Plains, the Mid-Mississippi to Ohio valleys, and the Mid-Atlantic. Delaware had the driest February-July on record, Illinois second driest, and Indiana and Wyoming each third driest. In total, 13 states ranked in the top ten driest category for February-July, and another 15 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 and also in the Southeast. August 2011-July 2012 ranked in the top ten driest category for seven states, with 14 other states ranking in the driest third of the historical record.

1-month state temperature ranks 3-month state temperature ranks 6-month state temperature ranks 12-month state temperature ranks

The dryness has been accompanied by abnormally warm temperatures at all time scales. July 2012 ranked as the warmest July in the 1895-2012 record for Virginia and second warmest for seven other states. In total, 32 states ranked in the top ten warmest category and an additional twelve ranked in the warmest third of the historical distribution. Colorado had its warmest June-July and May-July, 28 states had their warmest February-July, 33 had their warmest January-July, and 24 had their warmest August-July. For the last twelve months (August-July), only Washington state was not in the warmest third of the historical record or hotter.

Arkansas statewide Palmer Z Index, May-July, 1895-2012
Arkansas statewide Palmer Z Index, May-July, 1895-2012.

As noted earlier, excessive heat increases evapotranspiration and exacerbates drought. The combination of heat and dryness drove the Palmer Z Index to record or near-record levels for the following states:

Notably, Palmer Z Index value for May-July 2012 in Illinois was more severe than that for 1988, even though 1988 period was drier than that of 2012. The reason for this is May-July 1988 ranked only 19th warmest, thus illustrating the importance of temperature in exacerbating drought.

Primary Corn and Soybean Belt Palmer Z Index, April-July, 1895-2012 Percent area of the Primary Corn and Soybean Belt in moderate to extreme drought, January 1900-July 2012


Corn and Soybean Belt

The Primary Corn and Soybean agricultural belt has been especially hard hit by drought the last four months. This region, collectively, has experienced the second warmest and sixth driest April-July in 2012, resulting in the fourth most severe Palmer Z Index (behind 1934, 1936, and 1988). The extreme severity of the dryness and evapotranspiration demand over the last four months 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). By the end of July 2012, about 86 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 across parts of the Southwest this month, and Pacific frontal systems dumped above-normal precipitation in the Pacific Northwest. The areas in between experienced short-term drought during July. The rain that did fall brought relief to some areas and lowered the percent area in drought a few percentage points, but it was not enough to end drought in the West. Drier-than-normal weather has dominated from the Southwest and intermountain basin to the Central and Southern Rockies 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, 68 percent of the West was experiencing moderate to exceptional drought at the end of July, a 4 percent increase compared to June. The Palmer Drought Index percent area statistic was about 53 percent, reflecting a remarkable rise over the last seven months.

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


Historical Analogs

The persistent warmth and dryness of the last couple years have been so severe that the nationally-integrated Palmer Z Index has been consistently negative (water demand outstripping water supply) for the last 14 consecutive months. This is largely behind the rapid expansion of drought this year which has led to the largest percent area in moderate to exceptional drought in the 13-year USDM record and largest moderate to extreme drought area (based on the Palmer Drought Index) since the 1950s. In 2012, about 57 percent of the contiguous U.S. was in moderate to extreme drought at the end of July. The last time drought was this extensive was in December 1956 when about 58 percent of the contiguous U.S. was in moderate to extreme drought.

Even though the 2012 drought has reached a spatial extent that rivals the maximum extent of the 1950s drought, 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. When applied to the temperature pattern for July 2012, several Julys from the 1930s (1934, 1935, 1936) are a close match in many regions. July 1936 matches July 2012 fairly well for precipitation, and July 1954 matches July 2012 reasonably well for PDSI and PHDI (although there are other months from other years that match July 2012 for all of these climate indicators). When looking at the seasons from January-July through June-July collectively, the 1950s are the closest match for the Palmer indices (PDSI and PHDI) in 2012, and the 1950s and 1988 closely match the 2012 Palmer Z Index, but there is less consistency for temperature and precipitation.

The 2012 drought is the latest of a series of episodes which have covered a larger-than-average area of the nation beginning in the late 1990s. If the criteria for determining when this nationally-significant drought period started is ten percent or more of the country persistently in moderate to extreme drought, then the current period started around Spring 1999. The spatial extent of drought has waxed and waned from 1999 to 2012. Again, if ten percent is used as a criteria, then the 1999-2012 drought period has had three episodes, roughly 1999-2004, 2005-2009, and 2010-2012. During this time, ten percent or more of the country experienced moderate to extreme drought for a total of 140 months.

Percent area of the U.S. in moderate to extreme drought, January 1996-July 2012

Percent area of the U.S. in moderate to extreme drought, January 1926-July 1942

Using the ten percent criteria, the 1930s droughts started around May 1929 and ended in February 1942. Some part of the country experienced drought during the 1929-1942 period. Like the 2000s drought, the spatial extent of the 1930s drought waxed and waned. Again, if ten percent is used as a criteria, then the 1930s drought had three episodes, roughly 1929 to early 1933, mid-1933 to early 1938, and late 1938 to early 1942. During this time, ten percent or more of the country experienced moderate to extreme drought for a total of 148 months.


For the 1950s droughts, the ten percent criteria indicates the nationally-significant drought started around August 1950 and ended in September 1957. Some part of the country experienced drought during the 1950-1957 period. Unlike the 1930s and 2000s droughts, the spatial extent of the 1950s drought essentially expanded and stayed at a relatively large area for most of the drought episode (especially from late 1953 to early 1957). Again, if ten percent is used as a criteria, then the 1950s drought had essentially one episode. During this time, ten percent or more of the country experienced moderate to extreme drought for a total of 86 months. But the average monthly area was 36 percent, compared to 32 percent for the 1930s drought and 29 percent for the 2000s drought.

Percent area of the U.S. in moderate to extreme drought, January 1946-July 1962

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.

Drought conditions and impacts are summarized by the National Weather Service office in Honolulu. SPI values are provided below.

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), July was drier than normal for Majuro, but near to above normal for the rest of the stations. Majuro has been drier than normal for the last three months. Total rainfall for the last 12 months (August 2011-July 2012) was near to above normal for all stations.

Pacific Island Percent of Normal* Precipitation
Station Name** Aug 2011 Sep 2011 Oct 2011 Nov 2011 Dec 2011 Jan 2012 Feb 2011 Mar 2012 Apr 2012 May 2012 Jun 2012 Jul 2012 Aug 2011-Jul 2012
Chuuk 144% 118% 97% 136% 125% 57% 181% 107% 40% 173% 131% 145% 120%
Guam IAP 102% 129% 135% 83% 103% 162% 94% 215% 121% 224% 107% 109% 122%
Kapingamarangi 162% 107% 57% 81% 124% 109% 71% 121% 102% 143% 179% 150% 121%
Koror 155% 266% 122% 62% 97% 36% 126% 121% 120% 122% 95% 94% 117%
Kosrae 122% 104% 154% 95% 174% 65% 185% 60% 84% 86% 99% 127% 110%
Kwajalein 144% 111% 125% 130% 84% 134% 114% 84% 68% 161% 117% 171% 124%
Majuro 108% 115% 115% 119% 91% 107% 65% 194% 97% 59% 81% 68% 100%
Pago Pago 72% 29% 137% 157% 75% 61% 98% 131% 90% 126% 115% 110% 101%
Pohnpei 138% 115% 77% 123% 110% 82% 138% 98% 45% 115% 100% 96% 101%
Saipan 93% 68% 140% 57% 110% 77% 183% 35% 33% 166% 118% 190% 104%
Yap 129% 156% 101% 112% 116% 33% 117% 185% 89% 142% 99% 106% 116%
* 1981-2010 Normal Median Precipitation
** Clicking on the station name will reveal a climatology graph of the normal monthly rainfall.

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 July 2012 was 7.94 million square km (3.07 million square miles), 21.35 percent below average. This ranked as the second smallest July sea ice extent on record for the Northern Hemisphere in the 1979-2012 period of record. The July 2012 Arctic sea ice extent was 20,000 square km (7,700 square miles) larger than the record small July extent, which occurred in 2011. During the month, the Arctic lost a total of 2.97 million square km (1.15 million square miles) of ice, with the daily sea ice extent reaching record lows briefly during the middle and end of July. July 2012 marks the 16th consecutive July and the 134th consecutive month with below-average Arctic sea ice extent. July Northern Hemisphere sea ice extent has decreased at an average rate of 7.1 percent per decade.

According to analysis by the NSIDC, Arctic sea ice continued to decline rapidly through July, much like it had in June. Sea ice coverage was below average across much of the Atlantic side of the Arctic, including the Kara, Laptev, East Siberian, and Beaufort seas. Near average sea ice coverage was observed in the Chukchi Sea. Sea ice was still blocking both the Northern Sea Route and the Northwest Passage at the end of July.

July'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 July 2012, at 8,300 km3 (1,990 miles3), about 700 km3 (170 miles3) less than the previous record low July volume which occurred in 2011. The July 2012 Arctic sea ice volume was also 65 percent lower than the maximum value in 1979, 55 percent below the mean value, and 2.2 standard deviations below the trend.

The July 2012 Southern Hemisphere sea ice extent was 16.7 million square km (6.4 million square miles), 2.21 percent above average and the 9th largest (26th smallest) July sea ice extent in the 1979-2012 period of record. Antarctic sea ice extent during July has increased at an average rate of 0.9 percent per decade, with substantial interannual variability.


Significant Event


According to NASA researchers, for several days during early July, nearly the entire Greenland ice sheet experienced a brief period of surface melting, including the summit of the ice sheet. During any given summer, about half of the ice sheet experiences some degree of melting, with most of the ice melt occurring at lower elevations. The melting was associated with a strong high pressure system bringing warmer-than-average conditions to Greenland. This phenomenon has not been observed on the Greenland ice sheet since satellite records began 34 years ago. However, ice core data indicates that such an event occurs about once every 150 years. The melting at the lower elevations in Greenland impacted population centers and infrastructure. The runoff flooded rivers, taking out structures and roads in and around Kangerlussuaq, a key transportation hub.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite observed a large calving event on Greenland’s Petermann Glacier along the northwestern coast on July 16th and 17th. The separated iceberg was about 32.2 square km (12.5 square miles), only half the size of the ice sheet calved in 2010, but marks the second large calving of the glacier in two years. This calving marks a retreat of the glacier, with the calving front occuring father upstream than previous events.

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

July Lower Troposphere
July Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.28 +0.50 Coolest 30th 1985 -0.45 -0.81 +0.14 +0.26
Warmest 5th 1998 +0.44 +0.79
RSS +0.20 +0.36 Coolest 28th 1985 -0.45 -0.81 +0.15 +0.28
Warmest 7th 1998 +0.51 +0.92
Year-to-Date Lower Troposphere
January–
July
Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.17 +0.31 Coolest 29th 1985 -0.31 -0.56 +0.13 +0.23
Warmest 6th 1998 +0.53 +0.95
RSS +0.06 +0.11 Coolest 23rd 1985 -0.41 -0.74 +0.13 +0.23
Warmest 11th 1998 +0.55 +0.99
Ties: 1991

Mid-troposphere

July Mid-troposphere
July Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.15 +0.27 Coolest 25th 1985 -0.39 -0.70 +0.09 +0.16
Warmest 9th 1998 +0.43 +0.77
Ties: 2007
RSS +0.08 +0.14 Coolest 21st 1985 -0.50 -0.90 +0.11 +0.20
Warmest 12th 1998 +0.45 +0.81
Ties: 1997, 1988
UW-UAH +0.21 +0.38 Coolest 27th 1985 -0.47 -0.85 +0.15 +0.26
Warmest 7th 1998 +0.51 +0.92
Ties: 2006
UW-RSS +0.12 +0.22 Coolest 25th 1985 -0.56 -1.01 +0.16 +0.28
Warmest 10th 1998 +0.52 +0.94
Year-to-Date Mid-troposphere
January–
July
Anomaly Rank
(out of 34 years*)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.01 +0.02 Coolest 19th 1989 -0.27 -0.49 +0.04 +0.06
Warmest 15th 1998 +0.54 +0.97
Ties: 2001
RSS -0.02 -0.04 Coolest 16th 1989 -0.29 -0.52 +0.07 +0.13
Warmest 17th 1998 +0.54 +0.97
Ties: 2011, 1990
UW-UAH +0.08 +0.14 Coolest 23rd 1989 -0.34 -0.61 +0.09 +0.17
Warmest 10th 1998 +0.63 +1.13
Ties: 2004, 1991
UW-RSS +0.05 +0.09 Coolest 21st 1989 -0.34 -0.61 +0.12 +0.22
Warmest 12th 1998 +0.62 +1.12
Ties: 2011, 1988
RATPAC* +0.05 +0.09 Coolest 42nd 1965 -0.86 -1.55 +0.14 +0.25
Warmest 13th 2010 +0.57 +1.03
Ties: 1987

*RATPAC rank is based on 55 years of data

Stratosphere

July Stratosphere
July Anomaly Rank
(out of 34 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH -0.37 -0.67 Coolest 9th 1996 -0.53 -0.95 -0.35 -0.62
Warmest 26th 1982 +1.10 +1.98
RSS -0.33 -0.59 Coolest 7th 1996 -0.49 -0.88 -0.27 -0.48
Warmest 28th 1982 +1.00 +1.80
Year-to-Date Stratosphere
January–
July
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 -0.63
Warmest 34th 1983 +1.07 +1.93
RSS -0.45 -0.81 Coolest 1st 2012 -0.45 -0.81 -0.29 -0.52
Warmest 34th 1992 +1.00 +1.80

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: 8 August 2012


Overview

During July, warm and dry weather brought ideal wildfire conditions to a large portion of the nation. The 2.01 million acres that were burned by wildfires was the 4th most on record, while the 9,869 fires was the 5th most in the 2000-2012 record for July.

1-Month Wildfire Statistics*
July Totals Rank
(out of 13 years)
Record 2000-2010
Average
Value Year
Acres Burned 2,014,395 4ᵗʰ Most 3,439,347 2004 1,610,142
10ᵗʰ Least
Number of Fires 9,869 5ᵗʰ Most 17,352 2008 9,220
9ᵗʰ Least
Acres Burned per Fire 204.1 5ᵗʰ Most 518.9 2004 192.1
9ᵗʰ Least
Year-to-Date Wildfire Statistics*
January–July Totals Rank
(out of 13 years)
Record 2000-2010
Average
Value Year
Acres Burned 4,088,349 6ᵗʰ Most 6,091,572 2011 3,505,217
8ᵗʰ Least
Number of Fires 37,576 10ᵗʰ Most 69,656 2006 50,013
4ᵗʰ Least
Acres Burned per Fire 108.8 4ᵗʰ Most 133.5 2011 70.6
10ᵗʰ Least

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

Discussion

As a whole, the contiguous U.S. had its record warmest and 28th driest July on record. Warmer-than-average temperatures were anchored across the Northern Rockies, most of the Plains, through the Midwest, and along most of the Eastern Seaboard. Cooler-than-average conditions were observed along the West Coast and the Gulf Coast. Dry conditions were present across the Central Plains and Midwest, while parts of the West and Southeast were wetter than average. Please see the U.S. temperature and precipitation report for additional information. The warm and dry weater created ideal wildfire conditions across a large portion of the country. According to the U.S. Drought Monitor, the percent area of the contiguous U.S. experiencing Moderate-to-Exceptional Drought (D1-D4) grew from 56.0 percent on July 3rd to 62.9 percent on July 31st. Drought improved across the Northeast and along the Gulf Coast, while the rest of the nation experienced continuing or worsening drought conditions. Drought conditions worsened by one to two categories across the Midwest, the Plains, the mid-South, and parts of the Intermountain West. The percent area of the contiguous U.S. experiencing Extreme-to-Exceptional Drought (D3-D4) doubled in size during July, from 10.3 percent on July 3rd to 22.3 percent on July 31st.

Significant Events


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


The Long Draw Fire which burned in a remote region of southeastern Oregon charred nearly 560,000 acres during July. The fire was ignited by a lightning strike on July 8th and was fully contained by the end of the month. The impacts of the fire were limited due to the rural location, with only a few ranchers losing cattle. The Long Draw Fire was the largest fire to impact Oregon since the 1840s, and surpassed 2002's Biscuit Fire in terms of acreage burned, which charred 500,000 acres. More than 480 firefighters were called to battle the blaze to prevent it from reaching populated areas.

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).

On July 1st, there were 57 large wildfires active across the nation. Five fires were burning in the Virginias, North Carolina, and Georgia, where dry conditions contributed to low 100-hour fuel moistures. Forty-eight large fires were active in the Intermountain West, from Arizona to Montana. Across the region, dry conditions for several months were exacerbated by record-breaking hot temperatures and windy conditions during the end of June, creating ideal conditions for wildfires at the beginning of July. Very high fire danger and KBDI values were widespread across the West, as well as low 100-hour and 1,000-hour fuel moistures. One large wildfire was active in central Alaska, where abnormally dry conditions had developed. One large wildfire was active in Hawaii, where dry conditions were observed. Two additional large fires were active in each Oklahoma and Missouri.


By mid-July, there were 32 large wildfires active across the nation, entirely across the western states — two in both Washington and Nevada; three in California and Montana; four in Oregon, Idaho, and Arizona; and five in Utah and Wyoming. The fires in the Northwestern states were accompanied by high fire danger and extremely low 10-hour and 100-hour fuel moistures. The wildfire conditions across the Great Basin were associated with high fire danger and low fuel moistures, while very low KBDI values contributed to the wildfire conditions in the Southwest.


On July 31st, there were 29 large wildfires active nationwide. Two fires were active in Florida, where high KBDI values were observed. Seven fires were burning across the Southern Plains and Mid-South where very warm conditions dominated during July, drying out fuels. High fire danger, very high KBDI values, and low 10-hour fuel moistures were observed across the region. In total, 20 fires were active across the western states of California, Colorado, Utah, Oregon, Idaho, Montana, and Wyoming. Warm and dry conditions during much of July contributed to high fire danger and high KBDI values, as well as lowering 10-hour, 100-hour, and 1,000-hour fuel moistures.


All Fire Related Maps


Citing This Report

NOAA National Climatic Data Center, State of the Climate for July 2012, published online August 2012, retrieved on April 16, 2014 from http://www.ncdc.noaa.gov/sotc/2012/7.