July Was Hottest Month Ever

National Weather Service - Thu 09:33 AM 08/09/2012

Previous warmest July for the nation was July 1936

The average temperature for the contiguous U.S. during July was 77.6°F, 3.3°F above the 20th century average, marking the hottest July and the hottest month on record for the nation. The previous warmest July for the nation was July 1936 when the average U.S. temperature was 77.4°F. The warm July temperatures contributed to a record-warm first seven months of the year and the warmest 12-month period the nation has experienced since record keeping began in 1895.

Precipitation totals were mixed during July, with the contiguous U.S. as a whole being drier than average. The nationally averaged precipitation total of 2.57 inches was 0.19 inch below average. Near-record dry conditions were present for the middle of the nation, with the drought footprint expanding to cover nearly 63 percent of the Lower 48, according the U.S. Drought Monitor.

Higher-than-average temperatures engulfed much of the contiguous U.S. during July, with the largest temperature departures from the 20th century average occurring across most of the Plains, the Midwest, and along the Eastern Seaboard. Virginia had its warmest July on record, with a statewide temperature 4.0°F above average. In total, 32 states had July temperatures among its ten warmest, with seven states having their second warmest July on record.

Other highlights:

* Drier-than-average conditions continued across the Central Plains and Midwest during July. Nebraska, Iowa, Illinois, and Missouri had July precipitation totals ranking among their ten driest. Maine had its fifth driest July on record.

* An active storm pattern in the Southwest contributed to California having its fifth wettest July on record and Nevada having its eighth wettest. Wetter-than-average conditions were also observed through the rest of the Southwest, along the western Gulf Coast, and through the Ohio Valley where West Virginia had its tenth wettest July.

* The warm and dry conditions over a large portion of the country were associated with ideal wildfire conditions. Over 2 million acres were burned nationwide during July due to wildfires, nearly half a million acres above average, and the fourth most on record since 2000.

Year-to-date: January-July

* The January-July period was the warmest first seven months of any year on record for the contiguous United States. The national temperature of 56.4°F was 4.3°F above the long-term average. Most of the contiguous U.S. was record and near-record warm for the seven-month period, except the Pacific Northwest, which was near average.

* The first seven months of 2012 were drier than average, ranking as 15th driest January-July on record. Below-average precipitation totals were observed for a large portion of the country, with 12 states having January-July precipitation totals among their ten driest. Above-average precipitation was observed for the Upper Midwest and the Pacific Northwest.

* The U.S. Climate Extremes Index (USCEI), an index that tracks the highest and lowest 10 percent of extremes in temperature, precipitation, drought and tropical cyclones across the contiguous U.S., was a record-large 46 percent during the January-July period, over twice the average value, and surpassing the previous record large CEI of 42 percent which occurred in 1934. Extremes in warm daytime temperatures (83 percent) and warm nighttime temperatures (74 percent) both covered record large areas of the nation, contributing to the record high year-to-date USCEI value.

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