The average temperature settled at 24.2C, smashing the previous record of 24.1C set in 2022, and the highest figure since records began in 1961, AEMET spokesman Ruben del Campo told a news conference.

Nine of the 10 hottest summers in Spain since 1961 have occurred in the 21st century, he added.

"We really are on this trend toward much hotter summers," the spokesman said.

Spain endured a record 16-day heatwave in August which fuelled wildfires that killed four people, and which the Carlos III Health Institute estimates caused more than 1,100 deaths -- mostly people older than 65.

Northwestern Spain, where the worst wildfires erupted, experienced "a very dry, or even extremely dry, summer," and this "combination of high temperatures and very low rainfall" created favourable conditions for fires, Del Campo said.

Of the 90 days of summer, 33 were marked by heatwaves, meaning "more than one in every three days this summer, we experienced extreme temperatures," he said.

Heatwaves were "more sporadic" in the previous century but have now become regular events, Del Campo added, noting the last summer in Spain without one was 2014.

AEMET has registered 77 heatwaves in Spain, with six going 4C or more above the average.

Five of those have been since 2019.

Scientists have warned persistently that human-driven climate change is resulting in more frequent and intense weather events worldwide.

Britain, Japan and South Korea also endured the hottest summers this year since each country began keeping records, according to their weather agencies.