intensified drought conditions.
Though temperatures have cooled in France and the UK, firefighters are still tackling blazes in Greece, Spain and Italy.
The fires in France's badly-hit south-west have started to be brought under control.
And as the heatwave moves north-east, low water levels are hampering transport on rivers in Germany.
In Greece, nearly 500 firefighters are tackling a blaze in Mount Penteli, to the north-east of the capital Athens, as the effects of the heatwave persist.
Three aircraft and four helicopters were deployed at dawn to help them tackle the blaze, the fire service said. Winds in excess of 80 km/h (49 miles/h) have made it harder to contain, the BBC's Stephen Ryan reports.
Almost all the water carriers in the region have been deployed, with additional support coming from most other regions in the country, the fire service said.
Hundreds have been evacuated from the surrounding areas, including eastern Gerakas, which is home to nearly 30,000 people. A paediatric hospital and the National Observatory of Athens have also been evacuated.
Fires have destroyed vast swathes of land in other areas of the continent too.
France has had some of the worst fires, particularly in the southwest region of Gironde, though conditions for tackling them have improved. Temperatures fell from 40C (104F) on Tuesday to the mid-20s on Wednesday.
"The conditions are favourable" to tackle the blazes, the mayor of La Teste-de-Buch - one of the affected areas in Gironde - told the BBC. Patrick Davet added, however, that it was necessary to stay "humble" as conditions can change.
French President Emmanuel Macron is due to visit the region later on Wednesday.
Spain has also been battling multiple wildfires.
Though one in the central province of Zamora has been brought under control, according to the local government, two large wildfires are still out of control in the north-western region of Galicia. A fire in the Gredos mountain range is also spreading east towards the Madrid region, the BBC's Guy Hedgecoe reports.