Key Points

• A new heat wave has been affecting France since the end of week 26/2025. In Brittany, the heat wave began on Saturday, June 28, when Météo France issued a yellow heat wave alert for Ille-et-Vilaine (32.3% of the region’s resident population). On Sunday, June 29, and Monday, June 30, Ille-et-Vilaine was placed under an orange heat wave alert and Morbihan under a yellow alert (22.5% of the regional resident population). Météo-France issued the same classification for July 1, 2025.

• A regional analysis of emergency care utilization indicates an increase in the iCanicule composite health indicator (including hyperthermia, dehydration, and hyponatremia) on Monday, June 30.

This trend falls within the expected fluctuations for the current meteorological conditions and is observable at the regional level, particularly in Ille-et-Vilaine and Finistère, which remained under a green alert.