A three-year-old has been found dead in a car in the Paris region, a police source said Thursday, the third such fatality of a child during the extreme weather this week.
Parents found the boy in "the car outside their home", the source said. Civil defence confirmed his death in the town of Saint-Gratien in the Paris suburbs.
France on Wednesday recorded the hottest day since measurements began in 1947, the national average temperature reaching 30C.
Paris mayor Emmanuel Gregoire earlier on Thursday reported that deaths were on the rise in the capital, but did not give a specific figure.
Temperatures in the capital reached 40.3C on Wednesday, topping 40C for the fourth time in 150 years.
Two children were found dead in a car in southern France on Monday.
The two victims, aged two and four, were found dead in their family's car in a residential parking lot in the town of Carpentras.