In France and the UK extreme heat warnings were issued while northern Spain recorded temperatures of 43C (109F) on Monday.
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 ever and experts say parts of France face a "heat apocalypse".
Several parts of France saw their hottest-ever days with the western city of Nantes recording 42C, the national weather office said.
Wildfires in recent days have forced more than 24,000 people to flee, with emergency shelters set up for evacuees.
Gironde, a popular tourist region in the southwest, has been hit particularly badly, with firefighters battling to control blazes which have destroyed over 15,000 hectares (37,066 acres) of land since last Tuesday.
"The idea that comes into my head is, it's a monster," Jean-Luc Gleyze, the president of the Gironde region said of the fires.
"It's a monster like an octopus, and it's growing and growing and growing in the front, in the back, on both sides. Because of the temperature, because of the wind, because of the lack of water in the air... it's a monster and it's very difficult to fight against it."
The UK had one of its hottest days on record on Monday, with a high of 38.1C recorded in Suffolk, in eastern England. Forecasters say Tuesday could see a top of 40C, which would be the highest temperature ever recorded in the country.
There were severe travel disruptions with trains cancelled and flights at London's Luton Airport suspended when part of the runway buckled under the searing heat.
On Monday, the Netherlands recorded its hottest day of the year so far. In the south-western town of Westdorpe, temperatures reached 33.6C.
And it is expected to be hotter on Tuesday, with temperatures forecast to top 39C in southern and central regions of the Netherlands.
Forecasters say the heatwave is heading north, with Belgium, Germany and Italy expected to see temperatures around 40C in the coming days.
In Spain and Portugal, more than 1,000 deaths have been attributed to the heat in recent days.
Temperatures in Portugal hit 47C on Thursday - a record for July. Most of the country has been placed under high fire danger by the national meteorological office IPMA.
Local media reports that 300 people from the northern Murça municipality have been evacuated due to the fire danger - authorities are anxious to avoid a repeat of 2017, when 66 people were killed in wildfires.