A powerful heatwave has tightened its grip on western Europe, shattering temperature records and pushing tens of millions of people into dangerous conditions. France recorded its hottest day since measurements began in 1947, with temperatures reaching 43.8°C in parts of the south-west and 40.3°C in Paris — only the fourth time in 150 years of records that the French capital has crossed the 40°C threshold. The UK registered its hottest June day on record at 36.1°C in Gosport, Hampshire, while Spain's daily average temperature hit its highest level since 1950. Red heat alerts remain in force across large swathes of France, the UK, Spain, Italy, and parts of northern Europe, with severe warnings also issued for Poland, Croatia and Hungary as the heat pushes eastward.

The human cost has been severe. At least 40 people have drowned in France in heatwave-related incidents since last Thursday, as people sought relief in rivers, lakes and the sea. More than 1,800 schools have been closed, train services cancelled, and landmarks including the Louvre and the Eiffel Tower shut early. Tens of thousands of homes in western France have lost power, leaving residents unable to use electric fans or close motorised blinds. French nuclear energy output was reduced as high river temperatures limited the water available for cooling reactors, and hundreds of thousands of poultry perished in the heat. Across Germany, barbecue bans have been introduced in several cities and authorities in multiple states are urging residents to conserve water amid fears of drought.

Scientists attribute the extreme conditions to a heat dome — a stationary high-pressure system in which sinking air compresses and heats as it descends, trapping warmth at the surface. Climate researchers say such phenomena are becoming more frequent, more intense and longer-lasting because of climate change. Europe is the fastest-warming continent, heating at roughly twice the global average rate, according to the Copernicus Climate Change Service.