‘Mind-bogglingly crazy’: climate experts alarmed by deadly spring heatwaves searing Europe

Malcolm Mistry knew it was going to get “very warm, very quickly” on Monday morning but a slow start out of bed delayed his plans for an early game of cricket with his son. It was already 10am by the time the pair arrived at the sun-soaked nets of their local club in south-west London, and to the embarrassment of the 48-year-old scientist, who played cricket in his youth, his body was struggling after just half an hour of bowling.

Had he continued for another hour, Mistry reckons he would have probably suffered from heatstroke. Had he and his son stayed until noon, they would have found themselves straining their bodies in direct sunlight while a nearby weather station logged the UK’s hottest May temperature since records began.

“I could feel I was panting a bit more heavily,” said Mistry, a leading climate and health researcher at the London School of Hygiene & Tropical Medicine. “That’s when I said to myself: ‘I need to stop here right now, immediately, before something happens.’”

The dark side of a gloriously hot European summer, excess mortality data compiled by experts such as Mistry shows, is an almost unfathomably large death toll – one that society rarely treats as a crisis. In 2024, summer heat in the EU claimed roughly three times more lives than car crashes, 16 times more than murderers, and more than 10,000 times more than terrorists.

This year, summer highs are striking before spring is even over. It may herald worse heat to come as parts of Europe brace for yet another torrid season of punishing extremes.

Temperatures over the weekend reached dizzying highs in the UK, which shattered its historical temperature record for the month by a full 2C. The Monday peak of 34.8C at London’s Kew Gardens was followed by a “tropical night” at Kenley airfield, with lows that did not drop below 21.3C, and was beaten on Tuesday with a high of 35.1C in west London. The Met Office said the temperatures would be “exceptional in the UK even in mid-summer, let alone in May”.

In France, where Monday highs surpassed 37.1C in the south-west, the national warning system was activated for the first time in May since it was introduced in 2004, and seven deaths were linked to the heat. Météo-France said abnormally hot periods had occurred in the month in previous years, “but nothing comparable to this one”. Spain may endure temperatures as high as 40C this week.

“Early-season heatwaves are especially hazardous because our bodies have not had time to acclimatise,” said Garyfallos Konstantinoudis, an environmental epidemiologist at Imperial College London, who estimates an extra 250 heat-related deaths will have occurred in England and Wales between Saturday and Monday.

“This exceptional spring heatwave is far more than an uncomfortable disruption to our sleep, work or study,” he said. “For vulnerable groups without access to cooling – particularly elderly people, the very young and those with underlying health conditions – these temperatures are quite simply dangerous and potentially fatal.”

The specific trigger for the record temperatures is an area of high pressure trapping heat. It comes on top of a global rise in average temperatures, which has increased the likelihood of extremes and made unprecedented highs an increasingly common reality.

Peter Thorne, a climate scientist at Maynooth University in Ireland, said: “We know beyond a shadow of a doubt” that the climate crisis had made heatwaves such as the latest one stronger and more likely. “But nevertheless, many of the records being set, particularly in the UK and France, are mind-bogglingly crazy.”

Farmers across the continent have begun to sound the alarm over weather projections in recent weeks, with a regional lobby group in the Netherlands recently warning of stress from prolonged heat and drought. Last month, the young farmers association in Aragón, in Spain, warned of a possible “catastrophe” for cereal crops because of extreme heat and lack of rain.

Scientists have warned that El Niño, a warming weather pattern projected to return in a particularly potent form this year, could lead to even hotter temperatures in 2026. Current projections foresee it reaching moderate strength in the summer and peaking toward the end of the year, though official scientific bodies have warned that projections made before the end of spring are subject to great variability.

“What matters much more than hype around an upcoming El Niño is that we have permanently shifted the climate,” said Thorne. He compared it to walking into a casino and rolling a seven on a six-sided dice.

“I expect numerous notable extremes in Europe this summer because that is our new reality – but exactly what, where, when and with what impacts is not predictable,” he added. “But if you don’t lose this time, there is always next year. And coming back to the casino analogy, in the end the house always wins.”