Hundreds more people were evacuated from their homes as wildfires blistered land in France, Spain and Portugal on Friday, and officials in Europe issued health warnings for the heatwave in coming days.
More than 1,000 firefighters, supported by water-bomber aircraft, have battled since Tuesday to control two blazes in southwestern France that have been fanned by scorching heat, tinder-box conditions and strong winds.
While temperatures dipped a little in Portugal, they were still expected to top 40 degrees Celsius (104 Fahrenheit) in some places, with five districts on red alert for extreme weather and more than 1,000 firefighters tackling 13 wildfires, authorities said.
In Spain, the Environment Ministry said it was helping tackle 17 wildfires across the country.
Officials are worried about the effects on people's health and on healthcare systems already challenged by the COVID-19 pandemic as the searing heat hits the continent, with warnings issued for worse to come in Britain in particular.
The World Meteorological Organization said on Friday the heatwave would trap atmospheric pollutants, degrading the air quality, especially in towns and cities.
"The stable and stagnant atmosphere acts as a lid to trap atmospheric pollutants, including particulate matter," Lorenzo Labrador, WMO scientific officer, told a Geneva press briefing.
"These result in a degradation of air quality and adverse health effects, particularly for vulnerable people."
From July 7 to July 13, Portugal registered 238 excess deaths due to the heatwave, the country's DGS health authority said.
"In this specific case, the excess can be attributed to the heatwave. In the last few days we have had very high, extreme temperatures ... and for a very long period," DGS chief Graça Freitas told Lusa news agency.
Health Minister Marta Temido said on Thursday the health system faced a "particularly worrying" week due to the heatwave and said some hospitals were overwhelmed.
Britain's weather forecaster issued its first red "extreme heat" warning for parts of England on Monday and Tuesday when temperatures are forecast to reach record highs.
"Exceptional, perhaps record-breaking temperatures are likely early next week," Met Office Chief Meteorologist Paul Gundersen said.
"Nights are also likely to be exceptionally warm, especially in urban areas," he said. "This is likely to lead to widespread impacts on people and infrastructure."
The highest recorded temperature in Britain was 38.7 C (101.7 F) recorded in Cambridge on July 25, 2019.
Hannah Cloke, climate expert at Britain's University of Reading, said the heatwave showed climate change is here and there is an urgent need to adapt.
"We are seeing these problems now and they are going to get worse. We need to do something now," she told Reuters.
"It's harder to cope with these types of temperatures in the UK because we're just not used to them."
In Portugal, the highest temperature on Thursday was recorded in the northern town of Pinhao at 47 C (116.6 F), just below the record.
In France's southwestern Gironde region, 11,300 people have been evacuated since the wildfires broke out around Dune du Pilat and Landiras. Some 7,350 hectares (18,000 acres) of land have been burnt, and authorities said the fires had not yet been stabilised.
In Spain, the wildfires that have been burning in parts of Extremadura, which borders Portugal, and the central Castille and Leon region forced the evacuation of four more small villages late on Thursday and on Friday.
The flames are now threatening a 16th century monastery and a national park. Several hundred people have been evacuated since the fires started and 7,500 hectares of forest have been destroyed in the two regions.
In Catalonia in the northeast, authorities suspended camping and sporting activities around 275 towns and villages to prevent fire risks and restricted farm work involving machinery.
Areas of Galicia and Extremadura remained on extreme alert for temperatures expected to touch 44 C (111 F). (Additional reporting by Benoit Van Overstraeten in Paris, Emma Pinedo and Christina Thykjaer in Madrid, William James in London and Emma Farge in Geneva Writing by Alison Williams Editing by Frances Kerry)