WASHINGTON: The contiguous United States has recorded its hottest summer ever, with scientists warning that the record heat should set off alarm bells over the increasingly severe effects of climate change.
The average temperature across the Lower 48 states during June-August reached 74.4°F (23.6°C), surpassing the previous record, set in 1936 and 2021, by 0.4°F, the National Oceanic and Atmospheric Administration (NOAA) said on Wednesday.
It’s official: 2026 dropped the mic and had the warmest summer on record for the contiguous U.S. How did you manage to stay cool during this historic summer?
Learn more about the August U.S. Report here: https://t.co/fi12yxK3Wl pic.twitter.com/9oom9BxwoX
— NOAA NCEI (@NOAANCEI) September 9, 2026
Four of the five hottest summers on record have now occurred in the past five years. The summers of 2022 and 2024 ranked fourth and fifth respectively.
Human-caused climate change
Scientists attributed the trend largely to human-caused climate change, driven mainly by the burning of fossil fuels. August was also the hottest on record since records began in 1895, with an average temperature of 75.6°F.
NOAA had previously reported that July 2026 was the hottest month ever recorded in the United States. “It is now time to stop acting surprised that our warming planet keeps getting warmer,” said Andrew Dessler, a climate scientist at Texas A&M University.
READ ALSO: June Breaks Heat Records Around the Globe, Affecting Millions
Zeke Hausfather, a climate scientist at Berkeley Earth, said the record summer was consistent with the effects expected from human-caused climate change.
“As the US and the planet as a whole warms, heat waves become both more frequent and more intense,” he said, warning that hotter summers increase heat stress, energy demand for cooling and pressure on infrastructure and public health systems.
Much above average temperatures
Most states recorded above-or much-above-average temperatures in August, while near-average conditions were limited to parts of the northern Plains and Midwest, according to NOAA.
Rainfall was also below average, with both August and the June-August period ranking among the driest third of records. By September 1, drought had affected nearly 60 per cent of the contiguous United States.
Lake Mead
Among the notable impacts, Lake Mead, the country’s largest reservoir, fell to its lowest level on record, reaching 1.5 feet below its previous low recorded in July 2022.
Meanwhile, severe storms brought heavy rainfall to several areas. Central Indiana received 11 inches of rain between August 11 and 17. Alaska’s average August and summer temperatures ranked in the warmest third on record, while Hawaii experienced its third-warmest August and a summer that also ranked in the warmest third.
