The Significant Impact of Extreme Heat on Health

Santé publique France has observed a significant increase in emergency care visits related to certain monitored health effects associated with heat (heatstroke, dehydration, hyponatremia, and fainting) nationwide, across all age groups. Starting on May 22, emergency departments and SOS Médecins recorded a gradual increase in visits, peaking on May 26 with 411 emergency room visits and 253 SOS Médecins calls. During this period, the use of emergency care for certain heat-related health effects (hyperthermia, dehydration, hyponatremia, and fainting) was twice as high in departments under an orange heatwave alert as in other departments.

Furthermore, the number of hospitalizations following emergency room visits for the monitored health indicators also increased starting on May 22, with more than 100 daily cases, and up to 230 hospitalizations on May 29. Hyperthermia and heatstroke primarily affected those under 15 and those aged 15–44, while dehydration and hyponatremia mainly affected people aged 75 and older.

The early onset of this unprecedented, historic, and exceptional heatwave for the month of May, according to Météo France, reveals more pronounced health impacts than those typically observed during heatwaves among younger populations (under 15) and adults (15–45).  This finding underscores the importance of strengthening prevention and adaptation measures in environments frequented by these populations, in addition to existing measures.

The Health Monitoring System

Under the auspices of Santé publique France and in collaboration with Météo France, the Heat Wave and Health Alert System (SACS) provides real-time monitoring of the health impacts of heat waves and supplies authorities with the data needed to adapt strategies for preventing and managing heat waves. As soon as a department in metropolitan France is placed under an orange or red heat wave alert by Météo-France, Santé publique France activates daily monitoring of emergency care use, with a focus on specific indicators of direct and rapid health effects (hyperthermia/heatstroke, dehydration, hyponatremia).

As a reminder, the summer of 2025 was the third-hottest summer since 1900, according to Météo-France. According to Santé publique France, the health impacts were significant throughout the summer and particularly during heatwave periods. Throughout the summer, more than 5,700 deaths were attributable to the population’s exposure to heat, with one-third occurring during heat waves.

The Public Health Management System

Throughout the season, based on alerts issued by Météo France and the situation monitored by Santé publique France, the Health Ministry’s Health Crisis Center and, at the local level, regional health agencies, prefectures, and local authorities will implement targeted actions to remind everyone of the proper precautions to take and provide assistance to the most vulnerable populations. 

The Ministry calls on every citizen to act responsibly and remain vigilant in the face of risks associated with extreme heat. Protecting everyone’s health is a collective challenge that requires everyone’s commitment.

Take the right steps to protect yourself and care for your loved ones during heat waves

Heat waves pose a major public health challenge, and their health impacts must not be overlooked. They can have particularly significant health effects, especially on vulnerable populations, including the elderly, isolated individuals, people with disabilities, those in precarious situations, as well as patients with chronic conditions, pregnant women, young children, and workers outdoors or in overheated indoor environments. Overexposure to heat and/or poor hydration can also affect the health of otherwise healthy individuals.

To limit these consequences of heat exposure, it is important to prepare by taking simple steps. To this end, recommendations are made available to the general public ahead of summer on the websites of the Ministry of Health and Santé publique France, to help people cope better with the heat (how to adapt your home to the heat, when to exercise, how to get around, etc.).

At the same time, and in the event of a heat wave, health authorities remind the public that it is essential for everyone to strictly follow effective preventive measures to protect themselves from the health effects of heat: 

• Drink water regularly without waiting until you are thirsty;
• Cool off and wet your body (at least your face and forearms) several times a day;
• Eat fresh, balanced meals and limit your consumption of coffee and tea;
• Do not consume alcoholic beverages;
• Avoid going outside during the hottest hours of the day (in the city, temperatures drop very late in the day); 
• Spend several hours a day in a cool place if your home is too hot (movie theater, public library, supermarket, etc.);
• Limit physical activity as much as possible, even if you are fit and healthy, and opt for low-impact sports;
• Keep your home cool (close windows and shutters during the day; open them in the evening and at night if it’s cooler);
• Check in on your most vulnerable loved ones, and don’t hesitate to ask for help when needed.

For swimmers, it is recommended: 

• Swim only in authorized swimming areas;
• Enter the water gradually by wetting your head and neck;
• Do not consume alcohol before swimming; 
• When with children, “never take your eyes off them and swim with them.”