Key Points

• The second heat wave of 2026—defined for each department as temperatures exceeding the departmental alert thresholds for at least three consecutive days—began on June 17, 2026.
• This update on excess all-cause mortality focuses on the period from June 17 to July 2. During this period, 92 departments were affected by this heat wave, representing 98.5% of the population of mainland France. This unprecedented heatwave—characterized by its early onset, intensity, and duration—exposed nearly the entire population to extreme heat during a time when school and work activities were still in full swing.
• Across all 92 departments, on the days affected by the heat wave, at least 5,764 excess deaths from all causes (+36.2%) were estimated based on the 21,674 observed deaths from all causes and the 15,910 expected deaths from all causes. This excess all-cause mortality during a heatwave is the highest observed since 2003, though it did not reach the levels seen then. More than half (56%) of the excess deaths occurred between June 25 and 27.
• An unprecedented excess in all-cause mortality was observed across all age groups aged 15 and older, highlighting the remarkable intensity and duration of the population’s exposure to heat throughout mainland France. People aged 75 and older accounted for two-thirds of this preliminary toll, with at least 3,719 excess deaths (+33.3%).
• All regions were affected by excess all-cause mortality, with the exception of Corsica, Occitanie, and Provence-Alpes-Côte-d’Azur, which were exposed to less intense heat during this period. The region most affected by excess all-cause mortality is Île-de-France, with 1,999 excess deaths (+81.2%).
• These preliminary estimates were compiled three weeks after the end of the heatwave period under study (June 17 to July 2) and are based on unconsolidated all-cause mortality data. (Data as of July 20).
• All-cause deaths observed during this heatwave increased across all settings: hospitals, homes, and nursing homes/retirement homes.
• These findings underscore the importance of implementing management and prevention measures to reduce the impact of heat on the population, without waiting to observe health impacts.