Video report by ITV News Europe Editor James Mates
The heatwave in Europe has seen Southern France placed on an unprecedented red alert and firefighters in Spain battle wildfires on a scale not seen for 20 years.
With temperatures in both countries set to exceed 44C, Germany, Poland, and the Czech Republic have also set new records for the month of June.
Government officials have urged caution and a warning that the worst could yet be to come.
The red alert in France signifies a “dangerous weather phenomenon” and is the first since the system was introduced in 2004 following a 2003 heatwave that led to 15,000 premature deaths.
The Sahara-style heatwave spreading over parts of Europe has been caused by an “enormous” reservoir of warm air and has been linked to the deaths of three swimmers on south coast beaches in France.
A 70-year-old man was believed to have been a victim of “thermal shock” after coming into contact with the water during the heat spell on Tuesday, according to French news outlet LCI.
Two other people, a 62-year-old woman and a 75-year-old man, reportedly died in similar circumstances.
Authorities in Milan, in northern Italy, said a 72-year-old homeless man had died at the city’s main train station after falling ill due to the heatwave.
Watch a clip of the Catalonia wildfires here
There is fear the fire in Spain will spread due to strong winds in the vicinity.
More than 500 firefighters and soldiers have been dispatched to try and bring the fire in the Catalan province of Tarragona that has so far burned across 5,500 hectares (12,355 acres) of land.
Fifty-three people have been evacuated from their homes, five roads remain cut off and the civil protection authorities have advised people not to enter the area unless absolutely necessary. Hundreds of sheep have died in the smoke and flames.
The gravity of the situation was voiced by the region's interior minister, Miquel Burch, who said in a tweet: ''We are faced with a serious fire that had been unpatented for 20 years. They have burned 3,500 hac. In 6 hours and it could reach 20,000. Let's be very aware that any irresponsibility may end up being a catastrophe. Maximum precaution.''
Water usage restrictions in France have also been increased to avoid potential shortages.
There are restrictions on cars in the country to limit air pollution.
The average high of 39.4C on Wednesday broke France’s previous June record, Météo-France said.
The country’s all-time highest temperature of 44.1C – recorded on 12 August 2003 at two spots in the Gard département – is expected to be broken by this summer's heatwave.
Zoos around mainland Europe are working hard to keep the animals cool, with traditional ice lollies being handed out.
Germany also broke its June temperature record, which dated back to 1947, with a 38.6C reading in Coschen near the Polish border.
Parts of Britain are also expected to experience hot temperatures on Saturday, with a high of 32C forecast in London.
Scientists have said Europe’s 2019 heatwave, like last year’s, is closely linked to climate change and that such extreme weather events will be many times more likely over the coming decades.