WASHINGTON, United States (AFP) — The contiguous United States endured its hottest summer since modern records began, the National Oceanic and Atmospheric Administration (NOAA) said Wednesday, in the latest sign of a warming trend driven by human-caused climate change.

Average temperature for the meteorological summer, defined as the June-to-August period, was 74.4 Fahrenheit (23.6 Celsius), exceeding previous records, set in 1936 and 2021, by 0.4F.

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 in the US since records began in 1895, with average temperatures of 75.6F.

Most of the mainland United 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.

It comes as a strengthening El Nino pattern, expected to be the most intense in decades, has begun unleashing extreme weather across the globe.

It is predicted to bring record heat to 2027, but could also help make 2026 the hottest year on record, surpassing 2024.

Meanwhile mainland Spain endured its hottest summer since records began in 1961, with an unprecedented 61 heatwave days across June, July and August, the national weather agency AEMET said on Wednesday.

The average temperature for those three months was 24.5C, 0.3C above the previous record from 2025 and 2.4C higher than the 1991-2020 reference period, AEMET said in a statement.

A string of exceptional summer heat waves have smashed temperature records across Europe this year, which scientists say human-driven climate change has intensified and lengthened.

AEMET said the 10 hottest summers on record in Spain have all come in the 21st century.

This year’s number of summer heatwave days obliterated the previous high of 41 from 2022.

Exceptional heat has also spilled over the traditional limits of summer, with high temperatures measured in late May and early September.

On September 2, the south-western municipality of El Granado reached 45.7C, equalling the temperature record for the month and marking the highest temperature in Spain this year.

The extreme heat has been linked to tens of thousands of excess deaths across Europe, upended daily life for millions in ill-adapted regions and disrupted the economy through drought and low river levels.

In Spain, the Carlos III Health Institute has estimated more than 5,000 heat-related deaths from June to August, a record since its statistics began in 2015.