France has issued a "red alert", its most serious warning, for four southern regions amid a spell of excessively hot weather, allowing local authorities to call off events and close public facilities if needed.
The departments that will be targeted by the alert are the Rhone, Drome, Ardeche and Haute-Loire, Environment Minister Christophe Bechu told reporters.
The alert became effective at 4pm local time.
It was the sixth time Meteo France triggered the red alert - part of the government's scheme to protect the population during periods of extreme weather - and the first such incidence this year.
Earlier, Meteo France had issued an orange alert for half of the country's territory, saying temperatures will reach between 35 and 38 Celsius in most of the affected departments.
Peaks of 41C were expected in the southwest and in the Rhone valley.
Temperatures are expected to rise to between 40C and 42C tomorrow afternoon in the southern departments of Ardeche, Drome, Vaucluse and Gard, Meteo France said.
In May, the World Weather Attribution, whose scientists study the link between extreme weather events and global warming, said extreme heat events would have been "almost impossible without climate change".
According to the World Meteorological Organization, Europe is the world's fastest-warming continent which has been heating at twice the global average since the 1980s.
Since the mid-1800s, the world has warmed an average of nearly 1.2C.
But in Europe, the figure is almost double, with the continent now 2.3C hotter than in pre-industrial times, the organisation said in a report at the end of June.
Greek firefighters struggle to contain wildfire
Elsewhere, hundreds of firefighters struggled to contain wildfires fanned by gale force winds in several parts of Greece as authorities warned most regions faced a high risk of new blazes.
More than 200 firefighters backed by 17 aircraft were battling a wildfire burning for the third day near the northern port city of Alexandroupolis, where 13 communities were evacuated as a precaution since the fire broke out on Saturday, the fire brigade said.
Cyprus said it was sending two firefighting aircraft.
"We are in a state of alert, as we will be tomorrow, due to very high temperatures and gale force winds," fire brigade spokesperson Ioannis Artopios said.
"We are facing extreme phenomena," he said.
In Greece's northern seaside city of Kavala, two firefighters were injured while trying to contain a blaze threatening homes in the village of Dialekto, the fire brigade said.
A wildfire also broke out in the village of Psacha near Evia, where more evacuations were ordered. More than 90 fires and five aircraft were fighting the flames, assisted by French firefighting forces, it said.
A total of 64 wildfires erupted across Greece in the last 24 hours, the fire brigade said.
More than 20,000 foreign tourists had to be evacuated from the holiday island of Rhodes in July as wildfires burned for a week, destroying hotels and resorts.
Meanwhile, firefighters in Spain also battled to stabilise a huge wildfire that has devastated forests on the island of Tenerife for six days.
Efforts to extinguish it have been hampered by the difficult terrain - made up of steep ravines and cliffs - and a recent heatwave leaving the pine forest bone dry.
"The worst is behind us," the Canary Islands' regional leader Fernando Clavijo said this morning on Cadena SERradio station.
"Today, we will keep on working, consolidating perimeters. We cannot talk about control yet, we'll see if we can stabilise all the fronts," he added.
Authorities yesterday allowed some of the 12,000 people evacuated from the villages of Arafo and Candelaria to return to their homes, Mr Clavijo said.
