After days of record-breaking temperatures in France, officials have warned people to adjust their behaviour, with Health Minister Stéphanie Rist saying there were risks to young people as well as the elderly.
Ristsaid "young people are also suffering from cardiac arrests". The ambulance service in Paris had seen four times more cardiac arrests than normal over a 24-hour period, said Rist, while stressing there were no confirmed figures for the number of deaths linked to the heatwave.
Paris mayor Emmanuel Grégoire said the mortality rate was on the rise in the capital.
"We must not believe we are invulnerable," he told French TV. "I am thinking especially about the youth... At about 19:30 last night... I saw 100 or so joggers on the street. Frankly, that's irresponsible."
"It's fine to take a couple of days off from exercising," he added.
Rist said everyone had to adjust their personal activity to the high temperatures: "Even if you are young and in good health with no underlying medical issues, this heat will affect you too."
Even cycling came with risks, she warned, from high temperatures that lasted a week, as people would start feeling faint and might fall and even end up in hospital.
Climate change is driving up temperatures around the world - but particularly in Europe. It is the fastest warming continent, heating up twice as fast as the global average, according to the Copernicus climate service.
This is causing increased summer heatwaves, greater pressure on Europe's water supply, and more intense wildfires. Last year, more than 1 million hectares burnt across Europe - a record level - with Spain particularly affected.
Although temperatures in Spain are set to peak at 38-39C in some areas on Thursday, forecasters say a cooler mass of Atlantic air is coming in, after the highest June temperatures were recorded this week, with 45.1C in the southern town of Andújar on Monday.
Spain's MoMo monitoring system for reporting temperature-related deaths, external has counted 213 fatalities between Sunday and Wednesday that could be linked to the heat, including 95 on Wednesday alone.
In Germany, overnight temperatures in the southwestern town of Bad Bergzabern did not fall below 26.2C on Wednesday night, equalling a national heat record set in 2019.
Germany's DWD weather service said large areas of the country were experiencing "heat stress" and DWD meteorologist Oliver Reuter said it was "quite likely" the heatwave would ultimately be seen as historic.
Luxembourg recorded its highest June temperature of 38.3C in Wormeldingen on Wednesday. A red alert level for "extreme thermal stress" has been extended in the grand duchy until Saturday night.
In Germany, Hamburg's half marathon has been cancelled on Sunday and national train operator Deutsche Bahn is offering free ticket cancellations over the next few days for anyone not wishing to travel because of the extreme heat. Czech Railways have told passengers they should consider postponing their trips if they do not have to travel.
Much of northern and southern Switzerland was put on maximum weather alert by MeteoSuisse, which warned of a "significant drought situation".
Temperatures across the Czech Republic were well into the 30s on Thursday and the ČHMÚ Hydrometeorological Institute said the heat would intensify , externalon Friday with temperatures climbing up to 40C at the weekend.
