Europe's hottest summer caused record heat stress: monitor

A record 52 percent of Europe was exposed to intense heat stress during the exceptionally hot summer that seared the continent this year, the EU's climate monitor said Friday.

Fuelled by climate change, the world's fastest-warming continent endured a relentless series of heatwaves that began unusually early in the spring, shattering temperature records and causing tens of thousands of excess deaths.

"One of the things that stands out for 2026 is that the heat was not only remarkable for its intensity, but also for its geographical extent," said Samantha Burgess, climate lead at the European Centre for Medium-Range Weather Forecasts (ECMWF), which operates Copernicus.

It was the continent's third warmest summer on record and the hottest for western Europe, with several countries reporting all-time temperature highs.

Four of Europe's top 10 heatwaves occurred this past summer alone, Burgess said in a media briefing, with August 2003 still ranking as the most severe ever recorded.

This left 52 percent of Europe exposed to "very strong" heat stress -- when temperatures feel hotter than 38C -- according to Copernicus.

Around 80 percent of the continent experienced "strong" heat stress, or feels-like temperatures of more than 32C, which occurred on a record 41 days by the end of the season.

Heat stress occurs when the body's natural cooling systems are overwhelmed, causing symptoms ranging from dizziness and headaches to organ failure and death.

"Summer 2026 demonstrated how heat stress is becoming both more widespread and more persistent," Burgess said, noting that it was the leading cause of weather-related mortality globally.

The summer was also marked by dry conditions that led to the lowest river flows since records began in 1992, disrupting freight transport and putting pressure on irrigation, nuclear reactor cooling and hydropower, according to Copernicus.

Drought conditions have been increasing over the last 45 years in Europe.

By the end of August, drought affected almost half of Europe, Burgess said.

"That's one of the defining characteristics of summer this year, that it was not a single record. It was the way that multiple records appeared together across the climate system," Burgess said.