France and Austria brace for first heat wave of 2026 as temperatures climb toward 38°C

Météo-France uses a national thermal indicator known as the ITN, a daily average of daytime and nighttime temperatures recorded at 30 stations across metropolitan France. A heat wave is declared when the ITN exceeds 23.4°C for three consecutive days, including at least one day at or above 25.3°C. By Wednesday and Thursday, minimum temperatures of 18°C, 20°C or even 22°C are expected, meaning the ITN will climb sharply, Perrot explained.

The forecaster added: "Mais ce sont des températures très chaudes, bien au-dessus des normales de saison." Daytime highs could approach 40°C in some locations, with Météo-France forecasting up to 38°C in Nevers, 37°C in Paris and Brive, 36°C in Lyon and 35°C in Toulouse on Thursday. The combination of long days near the summer solstice and short, mild nights — "Les nuits sont courtes, ce qui limite la baisse nocturne des températures" — is set to prolong the heat.

Perrot said the end of the episode or potential heat wave would depend on the cooling effect of thunderstorms expected later in the week: "La fin de l'épisode ou de la vague de chaleur dépendra de l'effet rafraîchissant d'orages prévus en fin de semaine." The June event, he noted, would occur very close to the summer solstice, "donc d'intervenir pendant les journées les plus longues de l'année."

How this compares to past heat waves

Météo-France also distinguished this episode from earlier heat events. The late-May spell saw the ITN reach 24.8°C, an unprecedented level for May, but officials classified it as a "heat episode" rather than a heat wave. France last experienced a comparable heat wave in June 2019, an exceptional event from 25 to 30 June. The national temperature record was set during that period, with 46.0°C measured in a village in Hérault.

In 2022, France endured a slightly earlier heat wave, from 15 to 19 June, during which temperatures peaked at 43°C. Scientists broadly agree that repeated heat waves are an unambiguous marker of global warming and that such events are expected to become more frequent, longer and more intense.

Austria: a week of building heat

Across the Alps, Austria is also preparing for a heat wave in the coming week. GeoSphere Austria meteorologist Alexander Ohms summed up the outlook in a single sentence: "Ab Mittwoch kommt hochsommerliches und sehr heißes Wetter auf uns zu." Early temperatures on Friday will reach 15 to 22°C, and daytime highs are expected to hit 35°C, especially in urban areas. The heat will be punctuated by recurring thunderstorms: "Begleitet wird die Hitze immer wieder von Gewittern."

Monday across Austria will be calmer, with the sun appearing at least intermittently nationwide and temperatures of 19 to 25°C. Light rain showers are possible in the north and central regions in the morning, with the southeast more likely to see isolated showers or thunderstorms in the afternoon as cumulus clouds build to high altitudes: "Am Nachmittag wachsen Haufenwolken am ehesten im Südosten bis in große Höhen empor, dort sind dann ein paar meist isolierte Regenschauer oder auch Gewitterzellen möglich." Mountain conditions in the west will become more stable from Monday onward.

Tuesday will begin with widespread sunshine, with temperatures climbing to 27°C before harmless clouds move in from the west in the afternoon. From Wednesday, summer will take full control, though an upper-level low will initially keep the air mass unstable and prone to showers and thunderstorms. Daytime highs of up to 30°C are already expected despite the surface high pressure.

Thursday will start widely sunny under high pressure, but convective clouds and warm thunderstorms are expected to form from hill and mountain areas by late morning, with the focus of precipitation in the south and southeast. Early temperatures of 13 to 21°C and daytime highs of 26 to 33°C are forecast. Friday is set to be the peak, with brilliant sunshine pushing temperatures to up to 35°C in urban regions, and local warm thunderstorms mainly in the west and south of the main Alpine ridge.

Storms and a wider climate context

GeoSphere Austria also warned of strong shower and thunderstorm cells, particularly in Lower Carinthia, southern Styria and southern Burgenland. Across both countries, authorities are urging residents to prepare for several days of intense heat, with overnight relief limited and thunderstorms likely to mark the transition out of the heat.

The forecasts come against a wider backdrop of rising concern about recurring summer extremes. In the Pacific, the aftermath of Super Typhoon Sinlaku has renewed discussion of the possible return of El Niño, a pattern that climatologists have linked to amplified heat episodes in Europe.