Thursday, June 18, 2026, will remain in France’s meteorological records. For the first time this year, the thermometer crossed the symbolic 40°C mark in mainland France, in the commune of Montmorillon, in Vienne, where sensors recorded 40.2°C. This crushing heat marks the peak of a heatwave described as the first heatwave of 2026, the 52nd since 1947.

A striking record for an unprecedented June heat episode

This heatwave did not settle in all at once: since the start of the week, temperatures have risen steadily. On Monday and Tuesday, intense heat gradually spread eastward across the country. On Wednesday, the heat intensified everywhere. On Thursday, the highest values were reached in central and central-western France.

Among the notable readings from June 18 were also 39.4°C in Tortezais in Allier, 39.3°C in Issoudun in Indre and 39°C in Châteaumeillant in Cher. These temperatures place these days among the hottest ever recorded in the month of June.

Half of the 52 heatwaves recorded in France since 1947 occurred after 2010, in only 15 years, compared with 60 years for the other half — Météo-France

What Météo-France forecasts for Friday and the weekend

This Friday, June 19, the situation is not improving. Strong to very strong heat is holding across most of the country, with particular intensification in the northeast. Values of 37 to 38°C are expected between Centre-Val de Loire, southern Île-de-France, Champagne and Burgundy. Île-de-France should exceed 35°C once again. Sometimes strong thunderstorms could break out over northern France in the evening.

For the weekend of June 20 and 21, coinciding with the summer solstice, Météo-France forecasts continued very hot weather. On Sunday in particular, a new inflow of very hot air could cause another marked rise in temperatures, with values approaching or exceeding 40°C in several regions: Poitou-Charentes, Centre-Val de Loire, Île-de-France and the Rhône valley. Nights will remain warm, especially Saturday night into Sunday.

Which regions are most affected?

While the May 2026 heat episode mainly affected the west and northwest of the country, this new heatwave is primarily affecting an axis from central-eastern to northeastern France. Centre-Val de Loire, Auvergne-Rhône-Alpes, Bourgogne-Franche-Comté and the Paris region are particularly exposed. Brittany and coastal areas along the English Channel are benefiting from milder temperatures thanks to maritime air flows.

In total, 53 departments were placed under orange heatwave alert this Friday, compared with 26 on Thursday. The expansion of the vigilance system reflects the rapid progression of this episode.

Health risks: who is most vulnerable?

Extreme heat is not just uncomfortable: it can have serious health consequences, especially for the most vulnerable people. Older adults, infants, pregnant women, people with chronic illnesses and those living alone are particularly at risk.

The main heat-related symptoms are:

• Dehydration: drink water regularly, without waiting to feel thirsty
• Headaches and nausea: early signs of heat illness
• Muscle cramps: often caused by the loss of mineral salts
• Heatstroke: an absolute medical emergency that can be fatal without rapid intervention

In the event of heatstroke, warning signs include body temperature above 40°C, mental confusion, absence of sweating and dry, burning-hot skin. Call 15 (SAMU) immediately.

Good habits during the heatwave

To get through this episode safely, here are the essential tips to follow:

• Keep your home cool: close shutters and curtains from the morning, ventilate at night
• Drink water regularly (at least 1.5 litres per day, more if you sweat)
• Avoid physical exertion between 11 a.m. and 9 p.m.
• Take cool showers or baths several times a day
• Check on vulnerable people around you
• Never leave a child or animal alone in a vehicle

To follow alerts in real time, consult the Météo-France vigilance map and enable heatwave notifications by department in the official app.

Environmental impact: drought and fire risks

Beyond health risks, this early heatwave is worsening an already worrying environmental situation. Soils are already very dry for June, and this heatwave is expected to intensify drought in several regions, particularly Aquitaine, Limousin and Alsace, where humidity levels could approach historic seasonal records.

The fire risk is also high in some areas, especially around the Mediterranean and in western regions. Dry vegetation combined with extreme temperatures creates conditions favourable to fire outbreaks. Lighting fires near forested areas is strongly discouraged.

A strong signal of climate change

This 52nd heatwave in France since 1947 fits into a long-term trend linked to global warming. According to Météo-France, heatwaves occurring even before the start of the calendar summer were rare before the 2000s. They are now increasingly frequent: two thirds of heatwaves since 1947 have occurred after 2000.

This episode also comes only a few weeks after an exceptional heat episode in May 2026, itself described as unprecedented because of how early it occurred. The likely return of the El Niño phenomenon from summer 2026 could further strengthen temperatures in the months ahead.

Faced with these changes, adapting to climate change — building insulation, greening cities, water management — is becoming an absolute priority for the decades to come.