Key Points 

Extreme heat, heat wave 

• From May 25 to 29, 2026, the departments of Calvados, La Manche, and Orne were placed under a heat wave alert by Météo-France, and La Manche reached an orange alert level from May 26 to 28.
• The ICanicule indicator (dehydration, hyperthermia, hyponatremia) began rising in emergency rooms as early as May 23 (two days before the heatwave alert was issued in Normandy) while it rose for SOS Médecins associations starting on May 25, reaching levels comparable to or even higher than those during the heatwaves of 2022 and 2023. It returned to expected values in early June, both in urban areas and in hospitals.
• In addition to the ICanicule indicator, significant increases were observed for heat-related illness and sunburn, particularly among SOS Médecins associations. An increase in burns was also observed, reaching levels similar to the peaks of previous years.

Arboviral Diseases 

• Several people residing in the region who had traveled to an endemic area contracted an arbovirus disease and were reported as imported cases since the start of enhanced surveillance: these include 8 cases of dengue fever, imported from Martinique, French Polynesia, and Sri Lanka. 
• No indigenous cases of arboviral diseases have been reported in Normandy since the resumption of enhanced surveillance on May 1, 2026.

Skin and allergic conditions

• Increases in healthcare visits for insect bites, allergies (hives, conjunctivitis), and various skin conditions were observed during the last week of May, both in emergency rooms and at SOS Médecins clinics, primarily among children under 15 years of age.
• These increases occur against a backdrop of high grass pollen levels (driven by strong sunlight) as well as the presence of processionary caterpillars (with light, volatile, and stinging hairs), all of which expose people to environmental allergens that are easily dispersed during hot weather.