Key Points

• This update on excess all-cause mortality focuses on the period from July 27 to August 20, 2026. During this period, 79 departments across all regions of mainland France were affected by this heat wave, representing 89% of the mainland population. According to Météo France, this heat wave was particularly long on a national scale and matched the longest heat wave ever recorded (July 1983).
• For all 79 departments, taking into account the number of days affected by the heat wave during this period for each department, at least 817 excess deaths from all causes (+5.2%) were estimated based on the 16,552 observed deaths from all causes and the 15,735 expected deaths from all causes.
• This excess all-cause mortality affects almost exclusively people aged 75 and older, with at least 751 excess deaths (+6.7%).
• All regions experienced excess all-cause mortality, with the exception of Normandy and Occitanie. The region most affected by excess all-cause mortality is Bourgogne-Franche-Comté, with 140 excess all-cause deaths (+10.3%).
• These initial estimates were compiled three weeks after the end of the heatwave period under study (July 27 to August 20) and are based on unconsolidated all-cause mortality data collected by INSEE (data as of September 15).
• The number of all-cause deaths observed during this episode remained at a higher level compared to early June across all types of locations where deaths occurred.
• This initial estimate for the period from July 27 to August 20, 2026, complements the unconsolidated estimates previously produced for the heat waves from June 17 to July 2 and from July 3 to 20, 2026, which showed at least 5,764 and 1,243 excess all-cause deaths, respectively. The final estimate of excess all-cause mortality, consolidated for the entire summer and broken down by heat wave, will be presented in the summer report produced after the monitoring period. This report will describe the full range of impacts of the heat and heat waves observed during the summer of 2026.
• These impacts underscore the importance of implementing management and prevention measures to reduce the impact of heat on the population, without waiting to observe health impacts.