The June-August 2007 summer season ended with a long-lasting heatwave that set more than 2,000 new daily high temperature records across the southern and central U.S., according to scientists at NOAA's National Climatic Data Center in Asheville, N.C. The record heat helped make this the second warmest August and the sixth warmest summer on record for the contiguous U.S., based on preliminary data. At the end of August, drought affected almost half of the continental U.S. The global surface temperature was seventh warmest on record for the June-August period.
U.S. Temperature Highlights for Summer
- For summer 2007 (June-August), the average temperature for the continental U.S., based on preliminary data, was 73.8° F (23.2° C), which was 1.7° F (1.0° C) above the 20th century mean and the sixth warmest summer since national records began in 1895.
- This was the warmest summer for Utah and Nevada and it ranked in the top 10 warmest summers on record for 11 other states. Alaska had its fourth warmest summer on record. Only Texas and Oklahoma were cooler than average.
- The much warmer-than-average conditions in the Southeast and throughout the West contributed to above average residential energy demand for the nation. Using the Residential Energy Demand Temperature Index (REDTI - an index developed at NOAA to relate energy usage to climate), the nation's residential energy demand was approximately 8 percent higher than what would have occurred under average climate conditions for the season.
U.S. Temperature Highlights for August
- For the contiguous U.S., the average temperature for August was 75.4° F (24.1° C), which was 2.7° F (1.5° C) above the 20th century mean and the second warmest August on record, based on preliminary data.
- A severe heatwave persisted throughout much of the month across southern and central parts of the nation. More than 30 all-time high temperature records were tied or broken and more than 2,000 new daily high temperature records were established. - Raleigh-Durham, N.C., equaled its all-time high of 105oF Aug. 21. Columbia, S.C., had 14 days in August with temperatures over 100oF, which broke the record of 12 set in 1900. Cincinnati, Ohio, reached 100oF five days during August, a new record for the city.
- This was the warmest August in the 113-year record for West Virginia, Kentucky, Tennessee, the Carolinas, Georgia, Alabama, Florida and Utah. For the Southeast, the length, severity and area of the heat wave led to comparisons with events in 1983 and 1954.
U.S. Precipitation Highlights for Summer
- Overall, the summer was drier than average for the nation. Rainfall was below average in the Southeast, mid-Atlantic, Ohio Valley, the northern Plains and Northern Rockies.
- Texas had its wettest summer on record and Oklahoma its fourth wettest. The unusually wet period was punctuated by heavy and persistent rains in June and July that produced devastating flooding in the region. In the Southeast, this was the driest summer since records began in 1895 for North Carolina and the second driest for Tennessee.
- A hot and dry July in the Northern Rockies contributed to a fast start to the wildfire season, and August remained very active as warmer and drier-than-average conditions persisted in many areas. By early September, more than 7 million acres had burned across the nation, most of it in the western U.S.
U.S. Precipitation Highlights for August
- The record warmth and below-average rainfall in August led to an expansion of drought in the Southeast and parts of the mid-Atlantic and Ohio Valley. At the end of August, drought affected approximately 83 percent of the Southeast and 46 percent of the contiguous U.S., according to the federal U.S. Drought Monitor.
- Severe drought persisted throughout much of the West and an area that stretched from northern Minnesota to the Upper Peninsula of Michigan. - Part of the Midwest received record precipitation in August, as a persistent frontal system provided a focus for heavy rain and thunderstorms. Precipitation was two to three times normal for the month in a wide band across the central Midwest, and major flooding occurred in parts of a region that stretched from southeastern Minnesota to central Ohio. Iowa had its wettest August on record. - Tropical Storm Erin made landfall near Lamar, Texas, Aug. 16, bringing heavy rains to areas already much wetter than normal for the year. Widespread flooding ensued in southern Texas and Oklahoma.
- The combined global land and ocean surface temperature for August was the eighth warmest on record, 0.85° F/0.47° C above the 20th century mean. The global surface temperature for June-August (Northern Hemisphere summer) was the seventh warmest since records began in 1880. - Separately, the global land-surface temperature was the third warmest for August and the fifth warmest for boreal summer. The August ocean-surface temperature was the ninth warmest in the 128-year period of record as cooler-than-average conditions in the central and eastern equatorial Pacific indicated the ongoing development of a La Niña episode. - Hurricane Dean, the first major hurricane of the Atlantic hurricane season made landfall as a category 5 storm near Costa Maya, Mexico Aug. 21. This was the first Atlantic Basin hurricane to make landfall as a category 5 storm since Hurricane Andrew struck Florida in August 1992.
- Heavy monsoon-related rainfall that began in June continued to affect parts of South Asia in August. Millions of people were affected by flooding and thousands of flood-related deaths were reported.