National Climatic Data Center
12 September 2007
SIXTH WARMEST SUMMER ON RECORD ENDS WITH RECORD HEAT IN SOUTH
WIDESPREAD DROUGHT CONTINUES IN SOUTHEAST AND WEST
BOREAL SUMMER 7TH WARMEST ON RECORD FOR GLOBE
The June-August summer season ended with a long-lasting heatwave that produced more than 2000 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 6th warmest summer on record for the contiguous U.S., based on preliminary data. At the end of August drought affected almost half of the contiguous U.S. The global surface temperature was 7th 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 one of the ten 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 2nd 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 2000 new daily high temperature records were established.
Raleigh-Durham, NC equaled its all-time high of 105°F on the August 21, and Columbia, SC had 14 days in August with temperatures over 100°F, which broke the record of 12 set in 1900. Cincinnati, OH reached 100°F five days during August, a new record for the city.
The warmest August in the 113-year record occurred in eight eastern states (West Virginia, Kentucky, Tennessee, the Carolinas, Georgia, Alabama, and Florida) along with 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
The summer was drier than average for the nation as a whole. Rainfall was below average in the Southeast, mid-Atlantic, and Ohio Valley as well as the northern Plains and Northern Rockies.
A persistent atmospheric pattern brought much drier-than-average conditions to the Southeast and much wetter-than-average conditions to the Southern Plains. Texas had its wettest summer on record and Oklahoma its 4th 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% of the Southeast and 46% of the contiguous U.S., according to the federal U.S. Drought Monitor.
Severe drought persisted throughout much of the West as well as an area that stretched from northern Minnesota to the Upper Peninsula of Michigan.
Sandwiched between drought to the north and south, the central third 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.Global Highlights
The combined global land and ocean surface temperature for August was the 8th warmest on record, 0.85°F/0.47°C above the 20th century mean. The global surface temperature for boreal summer (June-August) was the 7th warmest since records began in 1880.
Separately, the global land-surface temperature was the 3rd warmest for August and 5th warmest for boreal summer. The August ocean-surface temperature was the 9th 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.
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.
Hurricane Dean, the first major hurricane of the Atlantic hurricane season made landfall as a category 5 storm near Costa Maya, Mexico on August 21. This was the first Atlantic Basin hurricane to make landfall as a category 5 storm since Hurricane Andrew struck Florida in August 1992.