Greece is experiencing a heatwave that began on Saturday and is expected to last 10 days. Temperatures are set to rise to 42ºC in some regions.
Greece is facing "an explosive cocktail of drought, high temperatures and strong winds", fire brigade spokesman Yiannis Artopoios told a briefing on Sunday evening.
Fires raged in the north, east and south of the country, including on the tourist island of Lesbos, where about 200 people were ordered to leave the village of Vryssa on Sunday to escape the flames.
Elderly women left the village carrying a few possessions in plastic bags, as thick smoke engulfed the first houses.
On Saturday, residents and tourists were told to leave the island's beach village of Vatera.
In the north-eastern region of Evros, hundreds of firefighters battled a wildfire that has been ablaze for four days in Dadia National Park, known for its black vulture colony.
Evros Governor Dimitris Petrovits told Athens News Agency that the authorities were doing all they could to protect locals and treat injured wildlife.
In the south, a fire in the Peloponnese caused the evacuation of three villages and a children's summer camp, while on the island of Crete a fire was raging inside a ravine.
In Spain, a heatwave that has persisted for two weeks was expected to produce record-high temperatures of 45ºC in the southern region of Cordoba.
This part of Andalusia registered Spain's highest-ever temperature, 47.7ºC, last year.
The national weather office said the relentless heatwave since July 9 and the lack of rain since the start of the year across the Iberian Peninsula meant there was an "extreme" risk of fires.
In all, fires in France, Spain and Portugal have already burnt more land so far this year than was destroyed in all of 2021.
The area — about 517,881 hectares — is equal to the size of Trinidad and Tobago.
The World Health Organisation said on Friday that Europe's heatwave had led to "more than 1,700 needless deaths … in Spain and Portugal".
Firefighters in Britain were battling blazes in London on Sunday, days after the mercury climbed to 40.3ºC, breaking the country's record.
The London Fire Brigade said it was dealing with more incidents than usual, with 205 personnel and 28 fire engines sent to tackle fires at three sites across the capital.
The brigade urged the public to cancel barbecues and remove rubbish from grassland.
The US meanwhile sweltered in scorching heat set to exceed already record-setting temperatures, worsening a wildfire burning out of control in central California.
Tinderbox conditions in California sparked a fire on Friday near the Yosemite National Park and its giant sequoia trees, two days after President Joe Biden warned that climate change represented a "clear and present danger".
In France, the government said on Sunday that it was bringing in rules to curb energy waste that adds to the greenhouse gas emissions fuelling climate change.
Shops will be ordered to keep their doors closed when their air-conditioning or heating is on or risk a fine, Energy Transition Minister Agnes Pannier-Runacher told RMC radio.
Leaving the doors open when the air conditioning is on leads to "20 per cent more consumption and ... it's absurd", Ms Pannier-Runacher said.