The Heat Wave and Health Alert System (SACS) established by Santé publique France makes it possible to study the health impact of heat waves.

Status Update During an Alert

During a heat wave alert, Santé publique France analyzes city emergency data (SOS Médecins) and hospital emergency department data daily. Since 2023, 15 days after the end of each heat wave, Santé publique France publishes an epidemiological report including an initial estimate of excess all-cause mortality observed during the heat wave. Once the alert has ended, Santé publique France assesses the heat wave.

• Heat Waves and Health in France. Bulletin of June 4, 2026.
• By region:
  • Heat Waves and Health in Nouvelle-Aquitaine. Bulletin of June 4, 2026.
  • Heat Waves and Health in Normandy. Bulletin of June 4, 2026.
  • Heat Waves and Health in Brittany. Bulletin of June 4, 2026.
  • Heat Waves and Health in Pays de la Loire. Bulletin dated June 4, 2026.
  • Heat waves and health in Île-de-France. Bulletin dated June 4, 2026.

Impact of heat on the summers of 2017–2025

Over the past 9 summers, 11,700 deaths have been attributed to the population’s exposure to heat during heat waves, and nearly 40,000 for the entire monitoring period.

Thus, nearly 30% of heat-related deaths occurred during heat waves, which accounted for only 4% of the days in the monitoring period. Heat-related mortality in the summer of 2025 is higher than in the previous summer but falls between the levels seen in 2022 and 2023, which were meteorologically hot summers (the 2nd and 5th hottest summers since 1900). Each summer and each heatwave episode has its own characteristics in terms of duration, intensity, and exposed population, making comparison with previous years complex. However, it is observed each year that heat accounts for 1 to 4% of summer mortality and 7 to 12% of mortality during heatwaves, figures that have remained stable since 2017.

At the national level

• Heat and Health. Summer 2025 Report. | Infographic

A significant increase in emergency room visits for heat-related illnesses

During the summers of 2015 through 2024, more than 155,000 emergency room visits and more than 33,000 SOS Médecins consultations were recorded in the SurSaUD® emergency and death surveillance system for metropolitan France, regarding the composite indicator tracked as part of the heatwave health management system (iCanicule), which includes heatstroke or hyperthermia, dehydration, and hyponatremia.

The use of emergency care for the iCanicule indicator is observed throughout the summer, including outside of yellow, orange, or red heatwave alert periods: thus, in recent years, up to 85% of emergency room visits and up to 80% of SOS-médecins consultations occurred outside of heat wave alert periods. However, peaks in emergency care use for iCanicule are observed during periods when a large portion of the population is affected by a heat wave alert.