Last month brought Hurricane Ida, numerous wildfires and devastating floods, capping off a summer of record heat and rainfall for many states throughout the country.
A summary of key findings from NOAA’s latest monthly U.S. climate report follows:
Climate by the numbers
Meteorological summer | June through August
The average temperature during meteorological summer for the contiguous U.S. was 74.0 degrees F, 2.6 degrees above average. This technically exceeds the record heat of the 1936 Dust Bowl Summer, but the difference is extremely small (less than 0.01 of a degree F).*
A record 18.4% of the contiguous U.S. experienced record-warm temperatures. California, Idaho, Nevada, Oregon and Utah each reported their warmest summer on record, as 16 other states had a top-five warmest summer on record.
The average summer precipitation total was 9.48 inches — 1.16 inches above average — making it the eighth-wettest summer in the historical record. Mississippi had its wettest summer on record while Alabama, Massachusetts, Michigan and New York had a summer that ranked among their five wettest. Meanwhile, Minnesota had its seventh-driest summer on record.
The average temperature for August across the contiguous U.S. was 74.0 degrees F, 1.9 degrees above average, making it the 14th-warmest August on record. New Hampshire and Vermont both had their warmest Augusts on record, while Maine and Massachusetts had their second warmest.
The average precipitation for August for the contiguous U.S. was 3.09 inches (0.47 of an inch above average), ranking 14th wettest in the 127-year record. Mississippi ranked fourth wettest while Tennessee had its fifth-wettest August. The city of Tucson, Arizona, saw its wettest August on record thanks to an active Southwest monsoon season.
Year to date | YTD, January through August
The average U.S. temperature for the first eight months of 2021 was 55.6 degrees F — 1.8 degrees above the 20th-century average — making it the 13th-warmest such YTD on record.
California and Maine each reported their third-warmest YTD, while 16 other states had a top-10 warmest YTD.
The nation saw an average of 21.19 inches of precipitation for the YTD, 0.48 of an inch above the long-term average, which ranked in the middle third of the record.
Mississippi had its third-wettest YTD on record, while Montana had its fifth driest. California, Minnesota and North Dakota all had a top-10 driest YTD on record.
Other notable climate and extreme events from the report
Hurricane Ida battered the Gulf Coast: On August 29, Hurricane Ida made landfall as a Category-4 hurricane near Port Fourchon, Louisiana, with 150-mph sustained winds. It was the second year in a row that a Category-4 hurricane slammed Louisiana. More than 1 million residents, and all of New Orleans, were without power. Grand Isle, Louisiana, took a direct hit: An unprecedented 100% of homes were damaged, and almost 40% were nearly or completely destroyed.
Multiple flooding disasters struck with lethal results: Devastating flash flooding with multiple fatalities occurred during August from Tropical Storm Fred in western North Carolina, Tropical Storm Henri across parts of the Northeast, and historical flooding from a complex of thunderstorms that moved across middle Tennessee. From late August into early September, Hurricane Ida also dumped an extreme amount of rain across Louisiana; the hurricane’s remnants submerged portions of the Northeast. With 35 fatalities reported during August, it was the deadliest month for flooding across the U.S. since Hurricane Harvey in 2017.
Wildfires swept through even more of California: The Dixie Fire in north-central California became the second-largest fire in the state’s history. The state’s Caldor Fire also grew rapidly during August, threatening communities in South Lake Tahoe. Air quality remains a concern across the U.S. due to increasing concentrations of airborne ash and fine particulates from smoke.