Health and fire warnings have been issued in countries across southern Europe, with temperatures expected to exceed 40C in some places over the weekend.
Italy, Greece, France, Spain and Portugal are among the countries affected – with the Spanish city of Seville forecast to hit 42C on Sunday.
Hot air from North Africa, which is spreading across the Balkans to holiday destinations such as Croatia, is contributing to the soaring temperatures.
BBC Weather says the heatwave is “very intense” for this time of the year – with the continent normally experiencing such high temperatures in July and early August.
In Spain, emergency staff have been placed on standby to deal with a surge in heatstroke cases especially among vulnerable people, including children, the elderly and those with chronic illnesses.
“It always gets super hot in Madrid, what surprises me is how early it’s happening – we’re still in June,” Marina, 22, told the Reuters news agency in the Spanish capital.
“This year is extreme. Last year, at least you could go out at this hour, but now? No way. It’s intense, and people are drinking more water,” Janeth, 47, said.
Italian authorities are advising residents in several cities, including Rome, Milan and Venice – where several A-list celebrities have gathered for the wedding of Amazon founder Jeff Bezos and TV presenter Lauren Sanchez – to stay indoors between 11:00 and 18:00 local time.
“There is no wind, a lot of humidity, we are sweating, and I’m suffocating at night,” Alejandra Echeverria, a 40-year-old Mexican tourist in Venice, told AFP.
France, meanwhile, has been experiencing a heatwave for more than a week. Orange heat alerts, the country’s second-highest warning, were issued for southern regions on Friday.
In the city of Marseille, municipal swimming pools are being opened free of charge until the end of the heatwave, while there have been calls in some places for schools to close to protect the health of students.
Yellow and amber alerts are also in place for parts of England this weekend, and temperatures in London may reach 35C on Monday. The heatwave is forecast to last until Tuesday evening.
Wildfires have already struck some parts of Europe, including Greece, where coastal towns near the capital Athens erupted in flames that destroyed homes – forcing people to evacuate.
While it is hard to link individual extreme weather events to climate change, heatwaves are becoming more common and more intense due to climate change.
Scientists at World Weather Attribution, who analyse the influence of climate change on extreme weather events, say June heatwaves with three consecutive days above 28C are about 10 times more likely to occur now compared to pre-industrial times.
