The French sports minister, Marina Ferrari, posted condolences to the loved ones of a runner who died on Sunday in a Paris race.
Le Parisien newspaper reported that the 53-year-old man suffered a heart attack during the run in the capital's 20th arrondissement, and that firefighters were unable to revive him.
It wasn't yet known if the cause of the runner's death was heat-related, but Ferrari suggested a possible link. Temperatures in Paris went as high as 32C in the afternoon.
"The events that occurred today (Sunday) during running races are a reminder that practising sports in extreme heat requires absolute vigilance," Ferrari said in an X post.
"My thoughts are with the family and loved ones of the runner who died in Paris, as well as with the people who were treated by emergency services."
In the southeastern city of Lyon, local media Actu Lyon on Monday reported the death of a woman who suffered heat stroke there during another sports competition, also on Sunday.
The national weather service, Meteo France, said temperatures are breaking records for the month of May, soaring past 30C in many parts of the country and forecast to last into the week.
The United Kingdom broke its record Monday for the hottest temperature recorded in May, after a heatwave was declared in several parts of the country.
People sought relief at beaches, parks and searched for shade on the holiday as the temperature hit 34.8C at Kew Gardens in southwest London, breaking the previous record of 32.8C set in 1922 and matched again in 1944.
The UK Health Security Agency has issued its first amber health alert of the year, warning of a rise in deaths, particularly among the elderly, at the hottest times of the day.
Next-level weather wildness is occurring ever more frequently as earth's warming builds.
Experts say unprecedented and deadly weather extremes that sometimes strike at abnormal times and in unusual places are putting more people in danger.
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