France is entering a new period of dangerous heat that is forecast to intensify and spread across most of the country during the coming week.
Twenty-two departments will be under an orange heatwave alert from midday on Monday, August 10. Temperatures are expected to rise further from Tuesday, with the heatwave potentially reaching its greatest extent and intensity between Wednesday and Friday.
The developing heat comes as severe thunderstorms move eastward from southwestern France, producing intense lightning, hail, heavy rain and powerful wind gusts.
Thirteen departments were under orange heat alerts on Sunday:
- Ain
- Alpes-Maritimes
- Ardèche
- Corse-du-Sud
- Drôme
- Gard
- Haute-Corse
- Haute-Savoie
- Isère
- Rhône
- Savoie
- Var
- Vaucluse
From midday Monday, the warning area will expand to include Allier, Alpes-de-Haute-Provence, Bouches-du-Rhône, Cher, Corrèze, Doubs, Hautes-Alpes, Jura and Saône-et-Loire.
Orange is the second-highest level on France’s four-tier warning system and indicates that dangerous weather capable of affecting health, transport and infrastructure is expected.
Temperatures climbed above 40°C (104°F) in parts of southern France on Sunday. La Chaîne Météo reported 41.4°C (106.5°F) at Céret, 40.8°C (105.4°F) at Villariès and 39.9°C (103.8°F) at Albi.
Montauban reached 39°C (102.2°F), Toulouse recorded 38.7°C (101.7°F), and Mont-de-Marsan climbed to 38.3°C (100.9°F).
Heat will spread across most of France
Monday and Tuesday will remain very hot across approximately three-quarters of the country. Afternoon temperatures will generally reach between 32 and 37°C (90 and 99°F).
A slight nationwide easing may occur on Monday, but temperatures in the southeast are expected to remain near their current extreme levels. Heat will then intensify again from Tuesday.
By Wednesday, unusually high temperatures are forecast across almost the entire country as a heat dome becomes established over France.
A heat dome develops when a persistent area of high pressure traps hot air beneath it. Sinking air suppresses widespread cloud development and rainfall, allowing temperatures to rise further each day.
Peak expected from Wednesday to Friday
The heatwave is forecast to reach its peak between Wednesday and Friday.
Afternoon temperatures will frequently range from 35 to 40°C (95 to 104°F), including in regions that do not normally experience such extreme heat. The most intense conditions are currently expected on Wednesday and Thursday.
Nights will also become increasingly uncomfortable. Temperatures may remain above 20 to 25°C (68 to 77°F) in some urban and southern areas, creating tropical nights with little opportunity for buildings or the human body to cool.
The heatwave is expected to continue through at least Friday. A gradual decline may begin on Saturday, August 15, as cloud and thunderstorms return from the west or northwest.
However, considerable uncertainty remains over the timing of the change. Dangerous heat may persist into the weekend across eastern and southern France.
Eight southwestern departments were placed under orange thunderstorm alerts on Sunday: Gers, Haute-Garonne, Hautes-Pyrénées, Landes, Lot-et-Garonne, Pyrénées-Atlantiques, Tarn and Tarn-et-Garonne.
Storms initially developed over southern Aquitaine before advancing toward the former Midi-Pyrénées region and farther east.
The strongest cells were capable of producing wind gusts between 90 and 110 km/h (56 to 68 mph), hail, frequent lightning and intense rainfall over short periods. Additional strong storms could affect the Massif Central, central-eastern France and the Alps.
Health risks increase during prolonged heat
High nighttime temperatures increase the danger because heat stress can accumulate over several days.
People should drink water regularly, limit strenuous activity and avoid direct sunlight during the hottest hours. Older adults, young children, people with chronic illnesses and outdoor workers face the greatest risk.
During thunderstorms, residents should move indoors, secure loose objects and stay away from trees, exposed ground and waterways.
Forecasts and warning levels may change as the heat dome strengthens. Stay up to date with the latest developments by subscribing to our newsletter.
