A deadly heatwave has claimed dozens of lives across Europe while disrupting power networks, forcing school closures and shuttering cultural sites as temperatures reach levels never before recorded in late June.
Britain set a new record high for June on 25 June 2025, while parts of France have endured overnight lows above 20°C for more than a week, with some areas recording minimum temperatures near 30°C.
The World Weather Attribution group of climate scientists confirmed the heatwave is the most severe ever recorded over the region studied. The international network found that human influence made the heatwave virtually impossible to occur naturally, with no contribution from El Niño weather patterns.
A comparable 1976 June heatwave would have been approximately 3.5°C cooler than current conditions. The World Meteorological Organization confirmed that greenhouse gas emissions have lifted the planet's mean temperature to approximately 1.4°C above 19th century baselines.
Research examining over 800 European cities found that 45% have either documented or are projected to reach their most extreme late-June heat stress conditions. Heat stress develops when the body's capacity to regulate temperature through perspiration breaks down.
The prolonged elevated temperatures at night — meteorologists define a "tropical night" as one where the thermometer stays above 20°C — prevent the body from recovering from daytime thermal stress, compounding health risks.
The World Weather Attribution analysis found that health impacts from this heatwave are just beginning to emerge. During the 2022 summer, more than 60,000 people died from heat-related causes during European heatwaves.
Europe is warming faster than any other continent, making the region particularly vulnerable to extreme heat events.
Clair Barnes, a research associate in extreme weather at Imperial College London, said the trajectory is clear. "We are not doing enough to slow the rate of global warming at the moment," Barnes said. "And so as that rate of warming continues ... we should expect to see record temperatures being exceeded more and more frequently."