A prolonged and exceptionally intense heatwave across western Europe has killed at least 40 people in France, most of them by drowning as they sought relief in rivers, canals and coastal waters, according to French authorities. Spain’s health services reported two elderly people dead from heatstroke, while Italian emergency rooms recorded a 15 per cent rise in calls and several fatalities are being investigated for links to the extreme temperatures. The French prime minister, Sébastien Lecornu, described the drowning toll since 18 June as a “tragic scourge”, noting that many victims were young. Two small children were found dead in a family car in Carpentras, south-east France, after being overcome by heat, local prosecutors said.

Across France, the national weather service Météo-France confirmed that Tuesday 23 June was the hottest day since records began in 1947, with an average temperature of 29.8°C and a peak of 44.3°C in Pissos, south-west of Bordeaux. The record was broken again on Wednesday, when the national thermal indicator reached 30°C. In Brittany, a transformer failure linked to the high temperatures left about 68,000 households without electricity, the Finistère prefecture said, adding that full restoration was not expected before late Wednesday. The United Kingdom recorded its hottest June day, with 35.8°C at Wiggonholt, West Sussex, surpassing a mark set in 1976, and the Met Office issued a rare red warning for extreme heat across much of England and Wales. Italy’s health ministry placed 16 cities under maximum alert, and Spain’s Aemet agency reported that Monday and Tuesday were the hottest June days in the country’s modern records.

The heat forced widespread closures. In France, education minister Édouard Geffray said about 6,000 schools had shut or adapted timetables, and the Eiffel Tower and the Louvre closed early. In the UK, more than 1,000 schools and nurseries were fully or partially closed, and rail operators urged passengers to travel only if absolutely necessary, with speed restrictions imposed to prevent tracks buckling. Dutch schools moved to “tropical” timetables, and Amsterdam opened free cooling centres. The pattern is being driven by an “omega block”, a stationary high-pressure system that traps hot air from North Africa and compresses it, a configuration that Météo-France said was comparable to the deadly 2003 heatwave.

The World Health Organization’s director-general, Tedros Adhanom Ghebreyesus, warned that the heatwave was “putting people’s health at risk” and that Europe is warming at roughly twice the global average rate. The International Federation of Red Cross and Red Crescent Societies cautioned that extreme temperatures can “quickly become a matter of life and death” for the most vulnerable. As of Wednesday evening, red alerts remained in force across large parts of France, the UK, Spain and Italy, with forecasters indicating that the heat would persist at least into the weekend and that the full human and economic toll was still being assessed.