Since Sunday, large areas of the Iberian Peninsula have recorded temperatures above 40°C in Spain and Portugal, where firefighters were battling wildfires.
Tinder-dry conditions have led to a fireworks ban in some towns before Bastille Day — one of France’s biggest celebrations — on Thursday.
In the mountains, the heat brings the threat of avalanches and people have died in Austria and Italy.
Firefighters were fighting a blaze that had ripped through 2,000 hectares of land in the central municipality of Ourem.
It had been brought under control on Monday but flared up again.
With temperatures set to climb past 40°C, Portugal's Prime Minister Antonio Costa urged “a maximum of caution”.
“We have experienced situations like this in the past and we will certainly experience them in the future,” he said.
The whole country is under a “situation of alert” for wildfires until at least Friday, raising the preparedness levels of firefighters, police and emergency medical services.
France is ready for a new heatwave to kick in this week, with temperatures closing in on 40°C.
A wildfire scorched through 800 hectares of pine trees just south of Bordeaux, forcing the evacuation of 150 residents, the local fire service said.
In the same area, close to the Dune of Pilat, which is Europe's tallest sand dune, another fire consumed about 180 hectares of old pine trees.
Prime Minister Elisabeth Borne has urged all government ministers to be ready to deal with the consequences of the heatwave, which is forecast to last for up to 10 days.
“The heat affects people's health very quickly, especially that of the most vulnerable,” her office said.
About 600 firefighters, supported by six water-bomber aircraft, are battling to bring the two wildfires under control.
“Important human and material resources are being deployed to master the fires (...) local and national reinforcements are expected,” said the local authority for the Gironde department, where the blazes are raging.
With Bastile Day on Thursday, the Gironde prefecture has banned all fireworks until Monday, July 18 in towns and villages in proximity to forests.
The UK's Met Office has extended its amber warning for a potentially deadly heatwave.
The warning for extreme heat for much of England and Wales is now in place until the end of Tuesday, with the hot spell expected to peak on Monday or Tuesday.
“Population-wide adverse health effects are likely to be experienced, not limited to those most vulnerable to extreme heat, leading to potential serious illness or danger to life,” the Met Office said.
Widespread disruption, including road closures and cancellations and delays to rail and air travel are also possible, as temperatures look set to soar into the mid-30s or above.
Parts of the country will be hotter than some of the world's top beach destinations, including areas in Jamaica, the Maldives and the Bahamas, with the hot weather set to last until the weekend.
The UK's record high for 2022 stands at 32.7°C, recorded at Heathrow on June 17. The hottest temperature ever in the UK was 38.7°C, in Cambridge in July 2019.
Temperatures are forecast to keep rising until Thursday, with highs of up to 44°C expected in Guadalquivir valley in Seville in the south.
Spain's health ministry warned the “intense heat” could affect people's “vital functions” and provoke problems such as heat stroke.
But for those who make a living working outdoors, it was a struggle. “It's hard because the temperature is a bit oppressive,” said Miguel Angel Nunez, a bricklayer in Madrid.
In the eastern region of Extremadura, 300 firefighters supported by 17 planes and helicopters battled a wildfire which ravaged 2,500 hectares, local officials said.
The blaze began on Monday because of a lightning strike and “will probably last several days”, said Guillermo Fernandez Vara, head of the regional government.
Between January 1 and July 3, more than 70,300 hectares of forest went up in smoke in Spain, the government said — almost double the average of the last ten years.
Five people were killed in an avalanche on Friday in the Austrian state of Tyrol.
The avalanche happened near the Austrian-Swiss border in the municipality of Spiss.
Italian authorities on Saturday put the final death toll of an avalanche in northern Italy at 11 and said all the victims had been identified.
A chunk of the Marmolada glacier in Italy’s Dolomite mountains dislodged on July 3, sparking an avalanche of ice, rock and debris down the mountain that is a popular hiking route in the summer.
Experts have said warming temperatures probably contributed to the cleaving, because the glacier has lost mass and volume for years and been melting more quickly than usual this summer, possibly destabilising it.
Swiss geologists fear the Marmolada mountain peak — the highest in the Italian dolomites — is in danger of collapsing and damaging the Swiss village of Kandersteg below.