Key Points

• In mainland France, the summer of 2020 was marked by three heat waves, one of which was particularly severe in northern France. The departments affected by at least one heat wave are home to more than 50 million residents, representing 77% of the mainland population.

• In the Centre-Val de Loire region, two heat waves caused alert thresholds to be exceeded: in the Cher department during the first episode in July and across all departments during the second episode in August. During the second heat wave, all departments were classified as orange alert by Météo France, but none were classified as red alert. For these periods, the impact on health was less significant than in 2019:

  • during the periods when alert thresholds were exceeded and for the affected departments in the region, 87 [52–116] excess deaths were estimated, representing a relative excess mortality rate of +16.2%. The August heatwave alone accounted for 68 deaths. People aged 75 and older accounted for the majority of excess deaths: 75 deaths across the two episodes (relative excess mortality of 20.6%). However, relative excess mortality was higher among those aged 65–74: 30.3% (25 excess deaths).

  • Heat-related conditions (defined by the iCanicule indicator, which includes hyperthermia, dehydration, and hyponatremia) accounted for 0.4% of emergency department visits and 0.5% of SOS Médecins calls during the first episode. During the second heatwave, this activity was higher, accounting for 1.0% of emergency room visits and 1.0% of SOS Médecins interventions. The hospitalization rate following an emergency room visit during these two heatwaves was 44.9% and 50.9%, respectively. While the impact was greater among those aged 75 and older, all age groups were affected.

The health impacts of heat observed in this study were not limited to these periods alone, as 75% of emergency room visits and 58% of SOS Médecins calls occurred outside of these two heat waves during the summer period (June 1 to September 21).