Key Points

A heat wave triggering the yellow and orange alert levels specified in the National Heat Wave Plan (PNC) affected 87% of the metropolitan population between June 17 and 25, 2017. This heat wave, which affected the Auvergne-Rhône-Alpes region from June 18 to June 25, was characterized by:

• an atypical weather situation due to its early onset and widespread nature, with all departments in the region affected,

• an impact on all-cause mortality, with a significant excess of deaths among those aged 15–64 (+29%, or +50 deaths). Mortality in the general population (all ages) and among those aged 65 and older increased, though it remained within the range of variations typically observed.

• An impact on healthcare utilization: 309 emergency room visits, 60% of which were followed by hospitalization (87% for those aged 75 and older), and 133 SOS Médecins consultations for heat-related conditions, affecting all age groups.

Furthermore, at the national level, 7 deaths were reported among workers, highlighting a particular impact within this population. One hypothesis to explain the observed impact on mortality among those aged 15–64 is the early timing of the heatwave, which occurred outside the summer vacation period.The health impacts observed during this early heatwave underscore the importance of strengthening prevention measures in the workplace, as well as among older adults.