With the “Heat Burst”, Extreme Storms to Fear in France this Week: what is this Phenomenon?
The historic heatwave in place in France is also causing storms, locally very violent, and they will increase by this Sunday 28th June 2026.
A heatwave never seen in France. These Tuesday 23rd June and Wednesday 24th June 2026 will be the hottest days ever recorded across France since measurements began in the 1940s, according to weather models.
“The drop in temperatures will begin between Friday 26th June and Saturday 27th June in the west of the country”, explains meteorologist Yann Amice. And a sequence d’thunderstorms will open, in a context boiling on the ground, with extreme phenomena to be feared locally. And in recent days, very locally, storms have already broken out, particularly in the Nord department or even in l’Eure and in the’Oise.
And this is also the case in Germany who is also drowning in the heat. Sometimes spectacular local storms were observed there, particularly in central Hesse where an impressive quantity of hailstones fell. In the village of Braunfels-Philippstein, a snow plow even had to clear streets blocked by hail, which reached the knees of the people firefighters !
And these days we are talking about another very rare phenomenon called “heat burst” (hot flash) which can occur in this context, an event meteorological rare but which can multiply in this context scorching.
This “heat burst” which is uncommon in France and is more common in the United States in the Great Plains.
After a stormy sequence, the thermometer flies away in a few minutes, and gains up to 10 sometimes 15°C and the wind can pick up at the threshold of the storm. This “heat burst” generally occurs at night, and occurs in the wake of a storm in a decline phase in overheated environments.
The “heat burst” does not form in an active storm, but in a weakening storm. The National Weather Service (NWS), the United States federal government agency responsible for providing weather forecasts, puts forward two elements for this “heat burst” to take place.
Two atmospheric elements: first, a dissipating storm or downpour. Second, a warm and dry mid-altitude atmosphere.
Thunderstorms form when a moist, unstable air mass is pushed upward. The moisture in the cloud condenses and then falls back as precipitation. Once the storm loses its updraft, it is said to be dominated by a downdraft.
And when this happens in the presence of a hot and dry mid-altitude atmosphere, as is currently the case in France, the humidity associated with the downdraft evaporates and initially cools this layer, accelerating its descent to the surface.
And in this case, the descending air stops cooling once all the humidity has evaporated, thus causing adiabatic heating (by compression, a bit like a bicycle pump that heats up when activated) and mixing of the hot layer (inversion).
The heat wave thus occurs when hot, dry air reaches the surface.
Winds associated with these heat bursts can tear off roofs, damage trees or simply move garden furniture.
This Tuesday 23rd June, the minimum temperatures will rise further, reaching 20°C to 26°C in the early morning over most of the country, 23°C to 26°C and sometimes 27°C, particularly from Brittany to Pays -de-Loire and northern New Aquitaine.
“We can expect very violent storms from this Thursday 25th June”
On the afternoon of this Tuesday, maximum temperatures will change relatively little compared to this Monday, remaining exceptionally high over most of the country. The very high heat will gain a little more ground towards the coast from Brittany to Normandy but also towards the south of Hauts-de-France. And many absolute temperature records will fall again.
The day of Monday 22nd June experienced “remarkable” temperatures with several absolute records broken: it was 40.6°C in Rennes (Ille-et-Vilaine), 40.9°C in Angers (Maine-et -Loire), 42°C in Saintes (Charente-Maritime), 41.9°C in Bordeaux (Gironde)…
In addition to these “heat burst” phenomena, which could still occur in the coming days in France, “we can expect very violent storms from this Thursday 25th June in Brittany, Normandy and Pays de la Loire in the Center”, already warns Yann Amice. Occasionally strong storms are also expected to increase and break out on Friday 26th June in the west of the country. And this risk will then extend to the northeast on Saturday June 27. And on Sunday 28th June, this risk should become widespread throughout the country.
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