Public health: at least 280 excess deaths during the August heatwave

At least 280 more deaths than normal, an excess of around 5%, were recorded in France during the heatwave from August 8 to 19, the second of the summer of 2025, the French public health agency announced on Thursday, September 11.

"This excess mortality is only observed among people aged 75 and over," the health agency specifies, recalling that it is still too early to establish a direct cause and effect relationship between these deaths and the high temperatures.

France, like other European countries, was hit in August by this episode of intense heat , the second of the summer after an initial heatwave in late June and early July. Globally, August was the third hottest month ever recorded.

The figures released Thursday by Public Health France provide an initial idea of ​​the mortality rate linked to this heatwave, which has affected just under half of France, while the negative effects of high temperatures are well documented: risk of dehydration, worsening of cardiovascular problems, etc.

However, this excess mortality may be linked to other causes, such as that previously announced for the June-July heatwave: Public Health France estimated it at around 480 excess deaths .

These calculations are based on all-cause mortality data from civil status offices and transmitted by INSEE, compared to an expected death figure based on the previous six years, excluding extreme events.

But, already, these initial data "underline the importance of implementing preventive measures to reduce the impact of heat, during heatwaves, but also throughout the summer" , warns Public Health France, while heat waves tend to increase against a backdrop of global warming.

In detail, the excess mortality observed during the August heatwave particularly affected Nouvelle-Aquitaine and Provence-Alpes-Côte d'Azur. They each recorded "at least 90 excess deaths – +7.9% and +7.7% respectively," according to the health agency.

Public Health France plans to provide a detailed assessment of mortality directly attributable to heat later this fall, not only during heatwaves but also throughout the rest of the summer.