The contiguous United States just endured its hottest summer since record-keeping began 132 years ago, according to a report released this week by NOAA's National Centers for Environmental Information, edging out the previous record set during the Dust Bowl summer of 1936.
The average temperature across the Lower 48 for June through August was 74.4 degrees Fahrenheit — 3.0 degrees above the 20th-century average and 0.4 degrees hotter than the prior record years of 1936 and 2021, according to the NCEI's national climate report. August alone was the warmest August on record, averaging 75.6 degrees, with daytime highs reaching 88.6 degrees on average — also a record. Nighttime lows were unusually warm as well, driven by a string of heat domes that settled over nearly every state outside Alaska and Hawaii.
Dry and Getting Drier
The heat arrived alongside a parched summer. Precipitation across the contiguous U.S. totaled 8.11 inches, about a fifth of an inch below average and in the driest third of the 132-year record; August itself was the driest since 2000. Texas logged less than 30 percent of its normal August rainfall, its third-driest August on record, while California had its fifth-driest summer since 2002. Indiana and Ohio were rare exceptions, each recording roughly double their normal August rainfall.
The dryness has pushed drought coverage sharply higher: as of September 1, 59.1 percent of the contiguous U.S. was in drought, up about 10.5 percentage points from early August, with the Interior West, Southwest, Great Basin and Northwest hit hardest. California, Nevada, New Mexico and Colorado each set records for their warmest August on record, and nighttime lows hit historic highs across much of the Southwest.
NOAA scientists attribute the extremes to a combination of factors, chief among them the recurring heat domes — large, slow-moving zones of high pressure that trap warm air for days at a time — layered on top of the long-term warming trend documented in NOAA's climate archives. The agency's findings, reported by CBS News, note that the West bore the brunt of the season's "punishing heat waves," which contributed to destructive wildfires and strained reservoirs already depleted by years of below-average snowpack.
NOAA's outlook for September favors above-average temperatures across the Southwest, Rockies, Great Lakes, Gulf Coast and Southeast, with drought expected to persist across the Great Basin, Northwest and Upper Midwest and to expand further across the southern Plains. Forecasters also flagged above-average wildfire potential for the Northwest, northern Great Basin, Upper Midwest, southern Plains and Florida heading into autumn — a sign that this record-breaking summer's effects are likely to linger well past Labor Day.
