In France and the UK, extreme heat warnings were issued while northern Spain recorded temperatures of 43C (109F) on Monday.
Deadly wildfires in France, Portugal, Spain, and Greece have forced thousands of people to evacuate their homes.
The UK is expected to see its hottest day on record and experts say parts of France face a “heat apocalypse”.
In Spain and Portugal, more than 1,000 deaths have been attributed to the heat in recent days.