Temperatures hit 47°C in parts of the Italian island Sardinia on Wednesday, inching close to the record 48.8°C, set in Floridia, Sicily, in August 2021.
Southern Europe's second heatwave in as many weeks has brought extreme temperatures to Mediterranean countries.
The Greek meteorological service had warned of a heightened risk of fires from Thursday, with temperatures over 40°C forecast in some areas, rising to a maximum of 44°C on Friday.
Firefighting teams from Poland, Romania and Slovakia were due to arrive in Greece on Thursday, to help battle wildfires, which were largely contained after razing swathes of forest and dozens of homes for days.
Israel pledged to send two firefighting planes, adding to the four from Italy and France that were already operating outside Athens.
In a round-the-clock battle to preserve forests, industrial facilities and holiday homes homes, evacuations continued for a third day on Thursday along a highway connecting the capital to the southern city of Corinth.
In the town of Mandra, 25 kilometres west of Athens, resident Varvara Paraskevopoulou said the flames reached her doorstep before the Fire Service did.
She described fleeing the fire on Tuesday and then returning to help neighbours trying to protect their properties.
“We extinguished what we could by ourselves and managed to save some homes. As you’ll see further up, three or four houses – residences and storage spaces – were burnt completely,” Ms Paraskevopoulou said.
Alessandro Miani, president of the Italian Society of Environmental Doctors, warned that the aging populations in Italy and other countries are a concern because heat-related deaths most commonly happen among the over-80s.
Heatwaves in Europe - in pictures
“The excessive heat together with humidity can make it difficult for sweat to evaporate, interfering with the body's ability to regulate its own temperature,” Mr Miani said.
The heat in Rome eased only slightly after a sweltering 42-43°C on Tuesday, while highs in Sicily reached 46°C and parts of Sardinia saw 47°C. Areas of Spain were as high as 45°C on Wednesday.
Amador Cortes, a resident in the southern Spanish city of Jaen, said people were doing their best to avoid the sun around midday and the early afternoon.
“The truth is, they take shelter at home with the air conditioning, with the fan. In the street, the elderly suffer a lot. Anyway, we have to put up with it,” he said.
In the southern Turkish city of Adana, a group of residents handed out desserts in the street, and many paid tribute to the US engineer Willis Carrier, who invented the air conditioner in 1902.
“The people of Adana really need air conditioners. God bless him for making such an invention,” city resident Mehmet Saygin told Turkey's DHA news agency.
The latest heatwave has fuelled concerns about climate change.
The World Meteorological Organisation said preliminary global figures showed last month was the hottest June on record.
“The extreme weather, an increasingly frequent occurrence in our warming climate, is having a major impact on human health, ecosystems, economies, agriculture, energy and water supplies,” WMO Secretary-General Petteri Taalas said on Wednesday.
“This underlines the increasing urgency of cutting greenhouse gas emissions as quickly and as deeply as possible.”
The firefighters were being sent to Greece as part of a European Union civil protection mechanism that includes the planned deployment of international crews to parts of southern Europe over the summer.