Key Points 

A period of high temperatures, possibly even a heat wave, has been underway in central-eastern France since Thursday, June 18 (S25). Temperatures are expected to rise in the coming days, with the heat wave potentially spreading more widely across mainland France.

High Temperatures, Heat Wave 

• Brittany experienced an early heatwave in S22 (May 26–28), affecting the entire region. Record-breaking temperatures were observed.
• The seasonal monitoring system has been active since June 1 and will remain so until September 15. All departments in Brittany have been under a green heat wave alert since May 30, 2026. In S23 and S24, health indicators returned to levels previously observed outside of periods of extreme heat.

Allergies

• Activity levels have returned to normal for this time of year following the very high peak in SOS Médecins consultations observed in S22.
• France Atmo is warning of an ongoing peak in grass pollen levels, particularly affecting Brittany.

ENT Conditions

• Activity related to ENT conditions was moderate to low. In Week 24, among children under 5, ENT conditions accounted for 11% of emergency department visits and 47% of SOS Médecins consultations. The virology laboratories at the Rennes University Hospital and the Brest University Hospital detected rhinoviruses/enteroviruses in 20% (6/30) and 23% (20/89) of the samples tested, respectively.