National Climate Report - August 2015
NCEI added Alaska climate divisions to its nClimDiv dataset on Friday, March 6, 2015, coincident with the release of the February 2015 monthly monitoring report. For more information on this data, please visit the Alaska Climate Divisions FAQ.
Maps and Graphics
Temperature and Precipitation Ranks
U.S. Percentage Areas
Supplemental August 2015 Information
- Summer 100°F Days
- August gridded temperature maps
- August gridded precipitation maps
- August daily temperature extremes
- Alaska temperature and precipitation divisional maps
- Year-to-date temperature evolution for select U.S. cities
- Year-to-date precipitation evolution for select U.S. cities
- January-August records and near-records
- Recurrent tidal flooding
August Average Temperature Departures
August Percent of Average Precipitation
- Climate Highlights — August
- The August average temperature for the contiguous U.S. was 73.0°F, 0.9°F above average and the 31st warmest on record.
- The August contiguous U.S. maximum (daytime) temperature was 85.8°F, 0.7°F above average, the 40th warmest on record. The August contiguous U.S. minimum (nighttime) temperature was 60.1°F, 1.1°F above average, the 25th warmest on record.
- Five states in the West– Arizona, California, New Mexico, Oregon, and Washington – and five states in New England – Connecticut, Maine, Massachusetts, New Hampshire, and Rhode Island – were much warmer than average during August, no state was record warm. Several locations in both the Northwest and Northeast were record warm for August, including JFK airport in New York City, New York; Caribou, Maine; Rome, Oregon; and Crescent City, California.
- Below-average August temperatures were observed across the Central Plains and Midwest, no state was record cold. In general, maximum temperatures were cooler compared to history than the minimum temperatures in the region.
- During August, there were 3,675 record warm daily high (1,442) and low (2,233) temperature records, which is about two and a half times the 1,498 record cold daily high (985) and low (513) temperature records.
- Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand during August was 37.2 percent above average and the 25th highest in the 1895-2015 period of record.
- The August precipitation total for the Lower 48 was 2.36 inches, 0.26 inch below average, and the 28th driest on record.
- Below-average precipitation was observed across parts of the West, South, and Northeast. Connecticut and Louisiana were much drier than average. Parts of the Northern Plains and Southeast were wetter than average. In the Southeast, the remnants of Tropical Storm Ericka brought beneficial rainfall at the end of the month to drought-stricken areas of southern Florida.
- South Dakota was much wetter than average during August. A heavy precipitation event in and around Sioux Falls, South Dakota at the end of the month brought torrential rainfall and flash flooding to the area. On the south side of the city, over 7.5 inches of precipitation was observed. According to the South Dakota State Climatologist, one of the South Dakota Mesonet stations recorded 4.00 inches of rain in 70 minutes with 1.35 inches of that fell in only 10 minutes.
- According to the September 1st U.S. Drought Monitor report, 30.4 percent of the contiguous U.S. was in drought, up 3.3 percent since late July. Drought conditions improved across parts of the Central Plains and Northeast, where it rained. Drought worsened across the Northwest, Northeast, and Southeast. Drought conditions degraded rapidly in parts of the South where hot temperatures and lack of precipitation quickly stressed manmade and natural systems. Drought conditions remain dire in the West, where wildfires charred over one million acres in August.
- Outside of the contiguous U.S., drought changed little in Alaska, Hawaii, and Puerto Rico. The remnants of several tropical systems impacted both Hawaii and Puerto Rico, but the beneficial rainfall did little to improve longer-drought conditions.
- Heavy rain associated with the remnants of three tropical cyclones, Hilda, Kilo, and Ignacio, resulted in Honolulu receiving 7.63 inches of rain during August, more than twice the previous record that occurred in 2004. The normal August precipitation total for Honolulu is 0.56 inch. The warm, moist, and tropical air associated with the tropical cyclones combined with record warm sea surface temperatures kept much of the state warmer than average during August. Hilo (79.7°F) and Kahului (82.9°F) experienced their warmest month, of any month, on record. Through September 5th, Kahului had experienced 52 days with the maximum temperature reaching 90°F. This bested the previous record of 49 days set in 1996. Honolulu has reached 90°F on 44 days in 2015 to-date, the sixth most on record.
- Climate Highlights — summer (June–August)
- The average temperature for the contiguous US during summer 2015 was 72.7°F, 1.3°F above the 20th century average. This ranked as the 12th warmest summer on record and warmest since 2012.
- The summer contiguous U.S. maximum (daytime) temperature was 85.1°F, 0.7°F above average, the 36th warmest on record. The summer contiguous U.S. minimum (nighttime) temperature was 60.3°F, 1.9°F above average, the fourth warmest on record.
- Eleven states across the West and Southeast were much warmer than average. Oregon and Washington each had their warmest summer on record. Oregon's summer temperature was 4.6°F above average, besting the previous record set in 2003 by 0.6°F. Washington's summer temperature was 5.3°F above average, beating the previous record set in 1958 by 1.1°F. Several cities, including Portland, Oregon and Seattle, Washington also had their warmest summer on record.
- Near- to below-average temperatures stretched from the Central Plains, through the Midwest, and into the Northeast. No state was record cold. Above-average precipitation across these areas suppressed daytime temperatures, contributing to the cool summer. This was the third consecutive cooler-than-average summer for many locations in the Midwest. According to information from the Midwest Regional Climate Center, most cities in the region had below average counts of 90°F days during the summer of 2015. A few examples of the lack of 90°F days through August 31st:
- Minneapolis: Four 90°F days in 2015 compared to 13 on average.
- Chicago: Seven 90°F days in 2015 compared to 14 on average.
- Indianapolis: Six 90°F days in 2015 compared to 14 on average.
- Cleveland: Three 90°F days in 2015 compared to 11 on average.
- Based on REDTI, the contiguous U.S. temperature-related energy demand during June-August was 51.1 percent above average and the 21st highest in the 1895-2015 period of record.
- The summer precipitation total for the contiguous U.S. was 9.14 inches, 0.82 inch above average. Driven largely by rainfall early in the season across the Midwest and Northeast, it was the 16th wettest summer on record.
- Nine states across the Midwest and Northeast had summer precipitation totals that were much above average. Record precipitation fell across the Ohio Valley during June and July, but a relatively dry August kept the seasonal rainfall totals off the record mark. Above-average precipitation also fell in parts of the West, mostly during July, but this is the dry season for the region and the rainfall did little to improve long-term drought conditions.
- Below-average summer precipitation was observed in the Southeast and Northwest. Washington had its ninth driest summer on record receiving only 52 percent of the seasonal average rainfall. The warm and dry summer in Washington created ideal wildfire conditions. By early September the Okanagan Complex Fire had charred over 300,000 acres and destroyed 176 homes. This is the largest wildfire on record in Washington, surpassing the Carlton Complex Fire that charred 250,000 acres in 2014. According to data form the National Interagency Fire Center, during summer 2015 wildfires burned nearly eight million acres in the U.S., the most since reliable record-keeping began in 2000.
- The U.S. Climate Extremes Index (USCEI) for summer was slightly above average for the contiguous United States. On the national-scale, extremes in warm minimum temperatures and days with precipitation were much above average. On the regional scale, the CEI for the Northwest and West were record high, due to warm maximum and minimum temperatures, the spatial extent of drought, and in the West days with precipitation. The USCEI is an index that tracks extremes (falling in the upper or lower 10 percent of the record) in temperature, precipitation, land-falling tropical cyclones, and drought across the contiguous U.S.
- Climate Highlights — year-to-date (January–August)
- The year-to-date average temperature for the contiguous U.S was 55.5°F, 1.6°F above average, the ninth warmest year-to-date on record and warmest since 2012. Above-average temperatures were observed in the West and Southeast. Thirteen states were much warmer than average, of which California, Nevada, Oregon, and Washington were record warm. Alaska had its second warmest year-to-date, with a temperature 4.0°F above average, only January-August of 1981 was warmer. Below-average temperatures were observed in the Midwest and Northeast.
- The January-August contiguous U.S. maximum (daytime) temperature was 67.4°F, 1.4°F above average, the 16th warmest on record. The January-August contiguous U.S. minimum (nighttime) temperature was 43.5°F, 1.8°F above average, the 10th warmest on record.
- Based on REDTI, the contiguous U.S. temperature-related energy demand during January-August was 17.1 percent above average and the 40th highest in the 1895-2015 period of record.
- The year-to-date precipitation total for the contiguous U.S. was 22.14 inches, 1.43 inches above average, and the 24th wettest on record. Above-average precipitation was observed across the central US, where eights states were much wetter than average. Oklahoma had its wettest January-August on record with a precipitation total 156 percent of average.
- Below-average precipitation was observed along both coasts. California, Connecticut, and Oregon each had precipitation totals that were much below-average. California had its fifth driest year-to-date receiving less than half the average precipitation.
- The USCEI for the year-to-date was 35 percent above average and the 17th highest value on record. On the national-scale, extremes in warm maximum and minimum temperatures, one-day precipitation totals, and days with precipitation were much above average. On the regional scale, the Northwest had its highest CEI for the year-to-date due to extremes in warm maximum and minimum temperatures, the spatial extent of drought, and one-day precipitation totals. The West had its second highest year-to-date CEI due to extremes in warm maximum and minimum temperatures and the spatial extent of drought. Only the January-August CEI of 2014 was higher in the West.
**A comparison of the national temperature departure from average as calculated by NCDC's operational dataset (nClimDiv), the U.S. Historical Climatology Network (USHCN), and the U.S. Climate Reference Network (USCRN) is available on our National Temperature Index page.**
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)
- The Northeast wrapped up August with an average temperature of 68.9°F (20.5°C), which was 0.8°F (0.4°C) above normal. Of the eight states that saw above-normal temperatures, seven ranked this August among their top 20 warmest: Rhode Island, 4th warmest; Maine, 5th warmest; Connecticut, 8th warmest; Massachusetts, 9th warmest; New Hampshire, 11th warmest; Vermont, 16th warmest; and New Jersey, 20th warmest. Departures for all states ranged from 1.2°F (0.7°C) below normal in West Virginia to 2.9°F (1.6°C) above normal in Maine. Kennedy Airport, New York and Caribou, Maine both had a record-warm August. Kennedy Airport's average maximum temperature was also record-warm. The site did not have a maximum temperature below 81°F (27.2°C) during August, which is the first time on record. Caribou set a record for the greatest number of consecutive days with a high temperature of 80°F (26.7°C) or higher with 10 such days from August 14-23. After a cool June, variable July, and warm August, the summer season in the Northeast averaged out to be normal, with an average temperature of 67.6°F (19.8 °C). Ten states were either normal or warmer than normal, with temperatures ranging from 0.5°F (0.3°C) below normal in Maine to 0.8°F (0.4°C) above normal in New Jersey, its 16th warmest summer on record. In addition, Rhode Island had its 19th warmest summer.
- August was a dry month for the Northeast with 2.99 inches (75.95 mm) of precipitation, which was 76 percent of normal. Eleven states were drier than normal, with four ranking this August among their top 20 driest: Connecticut, 11th driest; New Jersey and West Virginia, 15th driest; and Pennsylvania, 19th driest. Departures ranged from 50 percent of normal in Connecticut to 108 percent of normal in Maine. The Northeast had its 12th wettest summer on record, due primarily to an extremely wet June. For the season, the region ended up with 14.55 inches (369.57 mm) of precipitation, which was 117 percent of normal. Of the ten states that were wetter than normal, six ranked this summer among their top 20 wettest: Pennsylvania, 11th wettest; New Hampshire, 12th wettest; Vermont, 14th wettest; New York, 15th wettest; Maine, 18th wettest; and West Virginia, 19th wettest. Departures ranged from 85 percent of normal in Connecticut to 135 percent of normal in Maryland.
- At the beginning of August, parts of New England and New York (totaling 10 percent of the region) were abnormally dry or experiencing moderate drought. Spotty rainfall led to the expansion of abnormal dryness in these areas mid-month. Abnormal dryness was introduced in parts of New Jersey, Pennsylvania, Maryland, and West Virginia mid-month, as well. By the end of August, 23 percent of the Northeast was abnormally dry or under moderate drought conditions, according to the U.S. Drought Monitor.
- The Northeast experienced severe weather multiple times during August. A waterspout moved across Boston Harbor near Peddocks Island on the 4th. In addition, two tornadoes touched down in Pennsylvania during the month, an EF-0 on the 10th and an EF-1 on the 20th. Straight-line winds of up to 100 mph (45 m/s) caused damage, as did large hail, which was as large as tennis balls and baseballs in some areas. In addition, heavy rain triggered flash flooding, leading to road closures and water rescues.
- For more information, please go to the Northeast Regional Climate Center Home Page.
- Midwest Region: (Information provided by the Midwest Regional Climate Center)
- Precipitation in August was below normal for most of the Midwest. For many areas this was a welcome break from near record rainfall late in spring and early in the summer. Despite overall lower rain, parts of northwest Iowa and southwest Missouri each picked up more than twice their normal rainfall during the month. Cherokee, Iowa (Cherokee County) had 12.35 inches (314 mm), Randolph, Iowa (Fremont County) had 13.02 inches (331 mm), and Lockwood, Missouri (Dade County) had 10.49 inches (266 mm) in August. Summer (June, July, and August) precipitation total for the region ranked as the 4th wettest on record (1895-2015 period) with statewide totals ranking among the 10 wettest in Kentucky (2nd), Indiana (3rd), Missouri (5th), Illinois (6th), Iowa (7th), and Ohio (8th).
- The average temperatures for August ranged from near normal near the Great Lakes to 2 degrees F (1 C) below normal in the southwest parts of the region. Statewide August temperatures ranked among the coolest 40 years of the 121-year record (1895-2015) in the six central and southern states of the Midwest and fell closer to normal in the three northern states. Combined with the moderate temperatures in June and July, the August values brought the summer temperature average just below normal in the central parts of the Midwest while the northern and southern sections were very close to normal. The summer had below average number of days with very warm temperatures. Most cities in the region had below average counts of 90 degree F (32.2 C) and 95 F (35.0 C) days during the summer of 2015, often well below average. A few examples of the lack of 90 degree F (32.2 C) days: Minneapolis 4 days in 2015 and 13 on average, Chicago 7 compared to 14 on average, Indianapolis 6 compared to 14, and Cleveland 3 compared to 11.
- Drought was not a widespread concern in the Midwest despite the drier August conditions largely due to the plentiful rains in the preceding months. In fact, crop conditions were more affected by too much rain early in the summer (flooding and ponding of water in fields) with roughly 20 percent of the corn and soybean crops in Missouri, Illinois, Indiana, and Ohio rated as very poor or poor and only about half the crops rated as good or excellent. Midwest rivers flooded with the heavy rains of early summer, mostly returned to their banks in the early days of August.
- Severe weather reports in August were spread across the Midwest. During the month, 25 of 31 days reported severe weather, though many days had only a handful of reports. The six days with no reports all fell on or after the 20th of the month when reports dropped off from the early parts of the month. August 2-3 and August 18 were some of the busiest days for severe weather in the region.
- 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)
- Temperatures were near average across much of the Southeast region during August. Mean temperatures were 1 to 3 degrees F (0.6 to 1.7 degrees C) above average across portions of Florida, southeastern Alabama and Georgia, and the west-central Carolinas. In contrast, northern portions of Alabama and Virginia recorded mean temperatures that were 1 to 3 degrees F below average. Tallahassee, FL (1892-2015) and Vero Beach, FL (1943-2015) observed their fourth and fifth warmest mean temperatures for August on record, respectively. In addition, Tallahassee tied for the third greatest number of August days (17) with a minimum temperature of at least 75 degrees F (23.9 degrees C) and tied for the fifth greatest number of August days (29) with a maximum temperature of at least 90 degrees F (32.2 degrees C). Mean temperatures were above average in Puerto Rico and the U.S. Virgin Islands. The warmest weather of the month occurred on the 4th and 5th, as a cold front approached the region from the north. Daily maximum temperatures exceeded the middle 90s F (34.4 to 35.6 degrees C) across a broad portion of the region extending from Alabama to North Carolina, with isolated locations reaching 100 degrees F (37.8 degrees C). The University of South Carolina station in Columbia recorded a maximum temperature of 105 degrees F (40.6 degrees C) on the 4th, which is the warmest temperature recorded in the region during the month. In contrast, the coolest weather of the month occurred on the 29th and 30th, as a Canadian high wedged into the region from the northeast. During this two-day period, daily maximum temperatures did not exceed 90 degrees F across much of the region with the exception of Florida, and daily minimum temperatures dropped below 65 degrees F (18.3 degrees C) across portions of the Carolinas and Virginia.
- Precipitation was highly variable across the Southeast region during August, which is typical for the late summer. The driest locations were found across portions of the Florida Panhandle, far southern Florida, northeastern North Carolina, and eastern Virginia, where monthly precipitation totals were between 10 and 50 percent of normal. Woodstock, VA (1890-2015) observed its driest August on record with only 0.58 inch (14.7 mm) of precipitation. Precipitation was also below normal across much of Puerto Rico and the U.S. Virgin Islands, where Coloso, PR (1905-2015) observed its driest August on record with only 1.2 inches (30.5 mm) of precipitation. The wettest locations were found across west-central Florida, northern Alabama, northeastern and coastal Georgia, and coastal South Carolina, where monthly precipitation totals were between 150 and 300 percent of normal. Both Tampa, FL (1890-2015) and Orlando, FL (1892-2015) observed their third wettest August on record with 16.47 (418.3 mm) and 15.86 inches (402.8 mm) of precipitation, respectively. In addition, Tampa recorded its wettest 3-day precipitation total for August (8.42 inches; 213.9 mm) from the 1st through the 3rd, and the 4.39-inch (111.5 mm) precipitation total observed on the 3rd was Tampa's fourth wettest August day on record. A CoCoRaHS station located approximately 5 miles north-northeast of Tampa recorded an astounding 25.43 inches (645.9 mm) of precipitation during the month. Two significant rainfall events affected Charleston, SC during the month, including a flash flood emergency in the downtown area on the 18th. On the 31st, Charleston International Airport (1938-2015) observed its second wettest August day and fifth wettest day all-time with 6.43 inches (163.3 mm) of precipitation.
- There were 417 severe weather reports across the Southeast during August, which is very close to the median frequency of 391 reports during 2000-2014. Approximately 95 percent of these reports were for damaging thunderstorm winds, typical for the late summer. At least one severe weather report was recorded within the region on all but two days during the month (24th and 31st), but nearly 25 percent (102) of all reports occurred on the 6th, as a slow-moving front approached the region from the north. On the 6th, a severe thunderstorm produced widespread damage at the North Carolina Zoological Park in Asheboro, resulting in temporary closure but no injuries to any park visitors or animals. Later that day, a thunderstorm microburst with maximum winds estimated at 90 mph occurred near Fort Mitchell, AL, resulting in significant tree damage and an automobile accident. Six tornadoes (5 EF-0s, 1 EF-1) were confirmed across the Southeast during the month, which is below the short-term (2000-2014) median of 10 tornadoes for the region during August. While four of the five EF-0 tornadoes occurred in Florida, the more destructive EF-1 tornado caused significant damage to two large retail stores in Troy, AL. Seven injuries were reported with this tornado. On the 13th, twenty-one Army Rangers were injured and required overnight hospitalization after lightning struck their training grounds on Eglin Air Force Base near Fort Walton Beach, FL.
- Drought conditions improved in some areas but continued to worsen in other portions of the Southeast during August. The percentage of the region under drought-free conditions (less than D1) remained around 76 percent throughout the month. Moderate (D1) drought was completely ameliorated in northern Alabama and decreased in coverage across central Georgia. However, moderate drought conditions developed across portions of southern Alabama, the Florida Panhandle, and east-central North Carolina, with a small area of east-central Georgia experiencing severe drought (D2) by the end of the month. The localized area of extreme (D3) drought expanded slightly but shifted westward in far southern Florida, while extreme drought conditions persisted over eastern Puerto Rico despite some beneficial rainfall from Tropical Storm Erika. High winds associated with Erika caused an estimated $20 million in losses from Puerto Rico agriculture, particularly in the plantain and banana plantations. Farmers in the Big Bend area of Florida resorted to pumping water out of fields and pastures due to excessive rainfall during August, and white mold and mildew were also reported in some locations.
- 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 )
- It was another relatively quiet month for the contiguous U.S. The majority of the country had average temperatures within 2.0 degrees F (1.1 degrees C) of normal and precipitation extremes were not widespread. There were some exceptions, however. On the warm side, areas of the West Coast along with portions of the Desert Southwest and New England had temperature departures that were generally 2.0-4.0 degrees F (1.1-2.2 degrees C) above normal. Meanwhile, on the cool side, much of the central U.S. had departures of 2.0-4.0 degrees F (1.1-2.2 degrees C) below normal. Precipitation varied across the country, but unlike the last few months, heavy precipitation was not widespread. Wetter areas included coastal portions of the Pacific Northwest, pockets of the West, an area stretching from southeastern Montana through eastern Iowa, and another swath stretching from southeastern Kansas and northeastern Oklahoma through portions of Georgia and Florida. Where rain fell in heavy bursts, some locations did experience flash flooding. Meanwhile, the eastern sides of Washington and Oregon, along with much of Idaho, Montana, California, Texas, and Louisiana were quite dry with many locations receiving less than 25 percent of normal precipitation. As a result, drought conditions intensified or developed in many of these areas. Smoke from wildfires has been a common occurrence this summer and August was no exception. The Pacific Northwest was the epicenter for wildfires this month where over a million acres have burned this season and winds brought smoke from these fires all the way to the High Plains and Midwest regions. The smoke had a wide range of impacts, including some benign and some harmful. For instance, smoke suppressed daytime tem-peratures this month, but also created beautiful sunsets. On the other hand, smoke also resulted in air quality issues, which caused respiratory problems for sensitive groups. Although smoke can reduce incoming solar radiation, which is important for crop development, there is no evidence that the smoke has negatively impacted crops.
- Average temperatures were near normal for much of the High Plains region this month. Temperature departures were generally within 2.0 degrees F (1.1 degrees C) above or below normal, but there were a few exceptions. For instance, the eastern halves of Kansas and Nebraska, along with southeastern South Dakota were on the cooler side with temperature departures of 2.0-4.0 degrees F (1.1-2.2 degrees C) below normal. On the warm side, south-central Colorado had temperature departures generally in the 2.0- 4.0 degrees F (1.1-2.2 degrees C) above normal range. Isolated areas had larger departures and a few locations ranked in the top 15 coolest or warmest Augusts on record, including Pueblo, CO (5th warmest), Colorado Springs, CO (9th warmest), Iola 1 W, KS (12th coolest), and Salina, KS (14th coolest). Pueblo, Colorado had its 5th warmest August with an average temperature of 77.6 degrees F (25.3 degrees C). Although 4.2 degrees F (2.3 degrees C) above normal, this could not beat the 1970 record of 79.8 degrees F (26.6 degrees C). Pueblo has records dating back to 1888. At the end of the month, minimum temperatures dipped to around freezing in western parts of the Dakotas and eastern Wyoming. August frosts are not unheard of in these parts, but are considered on the early side. On average, the first fall frost occurs in mid to late September. Hettinger, North Dakota dipped to just below freezing on the morning of the 24th with a low of 31 degrees F (-0.6 degrees C), while Hill City, South Dakota had a low of 32 degrees F (0.0 degrees C). Both locations set new record lows for the day; however, they have relatively short records. At this time, there is no indication that this light frost had any impact to crops.
- As expected for the summer, precipitation varied this month across the High Plains region. Much of the region was on the drier side; however, areas receiving less than 50 percent of normal precipitation were not widespread and generally occurred in southern Wyoming, central Colora-do, and pockets of Kansas and North Dakota. On the wet end of the spectrum, areas receiving greater than 150 percent of normal precipitation included a large swath running from southeastern Montana and northeastern Wyoming through South Dakota and into Minnesota and Iowa. Portions of eastern Nebraska and southeastern Kansas also received at least 150 percent of normal precipitation. Due to the wide range in precipitation, numerous locations ranked in the top 15 wettest or driest Augusts on record, including Pueblo, CO (6th wettest), Omaha, NE (6th wettest), Sioux Falls, SD (9th wettest); and Goodland, KS (3rd driest), Sidney, NE (5th driest), and Boulder, CO (11th driest). At the end of the month, an impressive heavy rainfall event occurred in Sioux Falls, South Dakota. The official August total that pushed Sioux Falls to its 9th wettest August was 6.57 inches (167 mm), with 2.60 inches (66 mm) falling on the 27th (period of record 1893-2015). This total is measured at the airport on the north side of town; however, locations on the south side of town received much more that evening. Several CoCoRaHS stations reported over 5.00 inches (127 mm) of rain and the highest amount was a whopping 7.52 inches (191 mm). According to the South Dakota State Climate Office, one of the South Dakota Mesonet stations recorded 4.00 inches (102 mm) of rain in a mere 70 minutes and 1.35 inches (34 mm) of that fell in only 10 minutes. These rainfall rates are very high and not typical for the High Plains region. Not surprisingly, this heavy rain event caused flash flooding, which submerged cars and damaged homes and businesses. Due to the heavy rainfall this year, many locations have already reached their annual average precipitation. Lincoln, Nebraska surpassed its annual average this month by 0.38 inches (10 mm) with a total of 29.33 inches (745 mm) so far this year. Meanwhile, Rapid City, South Dakota could be on track to have its wettest year on record. With 22.59 inches (574 mm) so far this year, 2015 already ranks as the 4th wettest year on record (period of record 1948-2015).Currently, Rapid City is 6.30 inches (160 mm) above normal for the entire year.
- The little drought that remained in the High Plains region improved over the past month. According to the U.S. Drought Monitor, the total area in drought (D1-D4) in the region decreased to under a half a percent. Every state in the region except for Wyoming is now drought free. At the end of the month, only a very small area of moderate drought conditions (D1) remained in southwestern Wyoming. Abnormally dry conditions (D0) were still present over western Wyoming, northwestern North Dakota, northwestern Kansas, and parts of western Colorado. However, cooler and wetter conditions eliminated D0 areas in Nebraska, South Dakota, and southern North Dakota. These cool, wet conditions at the beginning of the month allowed for the last area of D1 in Kansas to improve. Now that only D0 remains, this is the first time since early November 2010 that Kansas has been drought free. While not a major concern in the High Plains region at this time, drought rages on in parts of the West where conditions worsened over the past month. Much of Oregon, Washington, Idaho, and Montana had an expansion of extreme drought conditions (D3). For instance, Montana's D3 coverage expanded eastward and increased by about 5 percent. Although portions of the headwaters of the Missouri River are in drought at this time, streamflows are near normal. The outlooks show that this area could have a warmer and drier winter so conditions should continue to be monitored over the next several months.
- For more information, please go to the High Plains Regional Climate Center Home Page.
- Southern Region: (Information provided by the Southern Regional Climate Center)
- August temperatures in the Southern Region we generally near normal across much of Oklahoma, Arkansas, and Tennessee, with temperatures averaging between 0-4 degrees F (0–2.22 degrees C) below normal. Elsewhere temperatures were also near normal, but averaged between 0-4 degrees F (0–2.22 degrees C) above normal, except for the Trans Pecos Climate Division in Texas, where temperatures averaged between 4-6 degrees F (2.22-3.33 degrees C) above normal. The state-wide average temperatures for the month are as follows: Arkansas averaged 78.10 degrees F (25.61 degrees C), Louisiana averaged 82.70 degrees F (28.17 degrees C), Mississippi averaged 80.20 degrees F (26.78 degrees C), Oklahoma averaged 79.50 degrees F (26.39 degrees C), Tennessee averaged 74.20 degrees F (23.44 degrees C), and Texas averaged 83.40 degrees F (28.56 degrees C). For Tennessee, it was the fifteenth coldest August on record, while Texas experienced its twentieth warmest August. All other state rankings fell within the two middle quartiles. All records are based on the period spanning 1895-2015.
- August precipitation in the Southern Region varied spatially from extremely dry across much of Texas and southern Oklahoma, to very wet in northeastern Arkansas, northern Mississippi, and western Tennessee. The driest areas of the region occurred in northern Louisiana and in central Texas, where stations averaged between 0 to 25 percent of normal rainfall for the month. Along northeastern Arkansas and western Tennessee, stations averaged more than two times normal precipitation. The state-wide average precipitation totals for the month are as follows with: Arkansas reporting 2.88 inches (73.15 mm), Louisiana reporting 2.49 inches (63.25 mm), Mississippi reporting 2.92 inches (74.17 mm), Oklahoma reporting 2.44 inches (61.98 mm), Tennessee reporting 4.60 inches (116.84 mm), and Texas reporting 1.40 inches (35.56 mm). Louisiana experienced its tenth driest August on record, while Texas and Mississippi reported their twenty-sixth and twenty-eight driest August, respectively. Tennessee recorded its twenty-fourth driest August on record. All other state rankings fell within the two middle quartiles. All records are based on the time period spanning 1895-2015.
- Drier than expected weather over much of the region has resulted in the expansion of drought conditions throughout much of Louisiana, central Tennessee and eastern Texas. In Louisiana, most of the state is now experiencing moderate drought, with some severe drought conditions in the northern Parishes along the southern border of Arkansas. This severe drought extends through north eastern Texas and south eastern Oklahoma. In east central Texas, there is an small area of extreme drought.
- On August 17, 2015, a tornado in Covington County, Mississippi downed numerous tree limbs and power lines. Fortunately, there were no injuries or fatalities reported.
- In general, there was very little in the way of severe weather for the Southern Region.
- For more information, please go to the Southern Regional Climate Center Home Page.
- Western Region: (Information provided by the Western Region Climate Center)
- Near to above normal temperatures were observed throughout the West this month. Though the magnitude of departures was not extremely large, generally 1-4 F (0.5-2 C) above normal, several locations in the Southwest and Pacific Northwest reported one of their top-10 warmest Augusts. Areas of above normal precipitation were scattered across the West resulting from different atmospheric features.
- August marked the fourth consecutive month of widespread above normal temperatures in the Pacific Northwest. Rome, in the southeastern Oregon high desert, and Crescent City, along the coast in far northwest California, both experienced their warmest August on record at and average 73.9 F (23.3 C) and 61.0 F (16.1 C), respectively, which was 4 F (2 C) above normal at both locations. Records for both stations began in 1949. Portland, Oregon recorded its 3rd warmest August with an average of 72.4 F (22.4 C) and its warmest summer (June-July-August) on record at 72.2 F (22.3 C). Above normal temperatures were prevalent along the southern border of the West as well. Temperatures at Tucson averaged to 89.0 F (31.7 C), 3.7 F (2 C) above normal and the 3rd warmest August since records began in 1946. Average summer temperatures in Tucson tied 2013 for second warmest on record at 88.3 F (31.3 C).
- Two low-pressure systems, one in the middle and another at the end of the month, brought much-needed precipitation to western Washington and scattered areas of coastal Oregon northern California. Rainfall totaled 3.28 in (83 mm) in Seattle for the month, the 4th wettest August in a 71-year record. Eastern Washington and Oregon and much of California remained drier than normal, though these areas typically receive little summertime precipitation. Scattered areas of above normal precipitation were observed in the Intermountain West associated with thunderstorm activity. Dyer, in west-central Nevada, recorded 3.55 in (90 mm) for the month, nearly all of it falling on the 2nd. This August set the record for wettest month of any month in Dyer's 113-year record. In eastern Nevada, Elko observed 0.63 in (16 mm), 170% of normal August rainfall. Further east, Malad City in southeastern Idaho observed nearly 3 times its normal August precipitation at 2.27 in (58 mm) during the first week of the month. In the Southwest, areas of well above normal precipitation were observed in the elevated areas of northern Arizona. Pipe Springs, along the Utah-Arizona border, recorded 3.45 in (88 mm) for the month, 165% of normal. Winslow, Arizona logged 3.26 in (83 mm), 272% of normal and its 3rd wettest August in a 123-year record. Precipitation was generally below normal in New Mexico. Albuquerque reported only 0.32 in (8 mm) for August, 20% of normal and the 10th driest August since records began in 1897.
- The Southeast, Interior, and Northern regions Alaska observed above normal precipitation this month while the Southcentral and Southwest regions were drier than normal. In the Southeast, Juneau recorded 8.92 in (227 mm) for the month, 156% of normal and the 8th wettest August in an 80-year record. Year to date, 2015 is Juneau's wettest on record. Anchorage observed only 0.97 in (25 mm) of rain, 30% of normal for August. Further south, above normal rainfall was observed throughout Hawaii in association with Hurricanes Hilda, Kilo, and Ignacio passing near the state. Honolulu recorded 7.63 in (194 mm) of rain for August, more than twice the previous August record set in 2004. Warm, moist, tropical air associated with these storms, anomalously warm ocean temperatures, and persistent high pressure over the state kept temperatures well above normal. Many locations experienced their warmest month on record of any month of the year, including Hilo, Big Island at 79.7 F (26.5 C) and Kahului, Maui at 82.9 F (28.2 C).
- August 9: Flash flooding near Marble Canyon, northern Arizona: Heavy precipitation from thunderstorms produced flash flooding in the Marble Canyon area on the afternoon of August 9. A 25+ mile (40+ km) stretch of highway was closed due to the large boulders and mud deposited on the roadway.
- August (all month): Fires in Pacific Northwest, northern California: Large fires burned throughout the Northwest this month, concentrated in Idaho, western Montana, Oregon, Washington, and northern California. Lightning on August 14 ignited the Okanogan Complex Fire and it grew to be Washington's largest fire on record at over 300,000 acres (121,000 hectares) before being broken into two smaller fires for management reasons. The Soda Fire in southwest Idaho began August 10 and has consumed over 279,000 acres (113,000 hectares), displaced wildlife, and damaged locations of historic significance. The Rocky Fire in Lake County, northern California began July 29 and spread rapidly with high winds over the first couple days of August. The Rocky fire has burned over 69,000 acres (28,000 hectares) and destroyed 43 residences. The Rough Fire in southern Sierra Nevada was ignited by lightning July 31 and grew to over 77,000 acres (31,000 hectares) by the end of August. The fire threatens many natural and cultural resources and has disrupted recreation in the region.
- Hurricanes in central/eastern Pacific: Over the last days of August, Category 4 Hurricanes Kilo, Ignacio, and Jimena were all present in the central and eastern Pacific basins. This was the first occurrence on record of 3 major hurricanes (category 3 or better) in these basins at the same time.
- For more information, please go to the Western Regional Climate Center Home Page.