'Alarm bells ringing': US summer heat shatters record

The contiguous United States has endured its hottest summer on record, a new peak that scientists said should send alarm bells ringing over the increasingly dire impacts of climate change.

Among the Lower-48 states, average temperature for the June-to-August period was 74.4F (23.6C), exceeding the previous record, set in 1936 and 2021, by 0.4F, the National Oceanic and Atmospheric Administration said Wednesday.

That means that four of the hottest summers on record occurred within the past five years, with 2022 and 2024 taking fourth and fifth place respectively, with human-caused climate change due mainly to the burning of fossil fuels looming large over the trend.

This year also saw the warmest August since records began in 1895, with average temperatures of 75.6F.

NOAA had previously announced that July 2026 was the hottest of all months ever recorded in the United States.

"It is now time to stop acting surprised that our warming planet keeps getting warmer," Andrew Dessler, a climate scientist at Texas A&M University told AFP.

"This is occurring exactly as forecast by scientists literally decades ago. The interesting question is not whether we will keep breaking heat records (we will), but whether we're going to do anything about it or just stand there while the climate train runs us over."

The so-called "Dust Bowl summers" of the 1930s -- especially that of 1936 -- were fueled by drought and extreme heat combining with overplowing across the Great Plains.

"The record summer is certainly in line with what we expect from human-caused climate change; as the US and the planet as a whole warms, heat waves become both more frequent and more intense," climate scientist Zeke Hausfather of Berkeley Earth told AFP.

"It should absolutely send alarm bells ringing, as these hotter summers lead to increased heat stress, higher energy demand for cooling, and strain on infrastructure and public health systems."

Most states experienced above- to much-above-average August temperatures, with near-average conditions seen only in parts of the northern Plains and Midwest, NOAA said.

Precipitation was below average, ranking in the driest third on record for both August and for the June-August period.

Drought covered nearly 60 percent of the contiguous US -- not including Alaska and Hawaii -- by September 1, said NOAA.

Notable events included Lake Mead, America's largest reservoir, dropping to its lowest level on record, falling 1.5 feet below its previous low in July 2022.

Elsewhere, severe storms brought heavy rain, including in central Indiana, where 11 inches fell from August 11 and 17.

Alaska's average temperature during August and average summer temperature ranked in the warmest third among records, while Hawaii saw its third warmest August and a summer that fell into the warmest third.

Hawaii was also exceptionally wet: Hurricane Lala brought heavy rainfall contributing to its second-wettest August on record.

The data comes as a strengthening El Nino pattern, expected to be the most intense in decades, begins to unleash extreme weather across much of the globe.

It is predicted to peak between October and December and fuel record heat in 2027. But because of this El Nino's extreme strength -- with near-record ocean temperatures already seen in the tropical Pacific -- it could even push 2026 past 2024 as the hottest year on record.