Key Points

• In Brittany, nearly 1,000 visits to hospital emergency rooms or SOS Médecins due to heat waves were recorded during the summer, 5% of which occurred during heat waves. All age groups were affected, but people aged 75 and older were the most affected, followed by those aged 15–74.

• Heat-related mortality is estimated at approximately 300 deaths over the entire summer (3% of all-cause mortality observed), including about 50 during heat waves (≈ 11% of all-cause mortality observed during these episodes). Nearly three-quarters of these deaths involved people aged 75 and older, whether over the entire summer or during heatwave episodes.