The summer of 2023 was marked by intense and exceptional heatwaves during which numerous heat records were broken. What to expect this summer?
[Mis à jour le 13 février 2024 à 10h10] France experienced a scorching summer of 2023 with two episodes of very high heat, in August and early September. More than 200 cities experienced the hottest temperatures in their history during the back-to-school period during the episode of high heat: 39°C in Vienne and neighboring departments, 35°C in the south-east, particularly in Aix- in Provence, more than 35°C in the departments of Centre-Val-de-Loire, between 32 and 34°C in Brittany and 33°C in Ile-de-France. If the first days of September were scorching, the summer of 2023 broke records by being the 4th hottest summer since 1900 with the 40°C mark often exceeded and numerous temperature records were recorded by Météo-France during this heatwave.
2024 also promises to be very hot. Specialists are already warning. The National Oceanic and Atmospheric Administration (NOAA) has calculated the likelihood that 2024 will be one of the hottest years on record. According to her, there is a one in three chance that 2024 will be warmer than 2023, and a 99% chance that 2024 will rank among the top five hottest years ever. This warming is explained by the El Nino meteorological phenomenon that appeared in mid-2023. According to the World Meteorological Organization (WMO), El Nino could still have an impact on temperatures in 2024, as WMO head Celeste Saulo explained: “given that El Nino generally has the greatest impact on global temperatures after its peak, 2024 could be even hotter than last year.
What is a heatwave?
As a reminder, we speak of a heatwave when these four characteristics are combined:
- a period of intense heat;
- with temperatures five degrees higher than seasonal norms;
- the day and the night ;
- for three consecutive days.
What was the 2023 heatwave plan put in place?
On June 8, 2023, the government announced the various actions implemented as part of its heatwave plan in order to protect the population during extreme heat waves.
What are the recommendations to follow during the heatwave?
Heat wave, heat peak, heatwave and heat dome: what are the differences?
Heatwave and heatwave are two different things. To speak of a heatwave, temperatures must be five degrees higher than seasonal norms, both during the day and at night, for at least three days and three nights. The heatwave temperature threshold therefore differs depending on the departments and regions. Heat waves most often occur in France in July and August. You have to be vigilant from June onwards. High temperatures, even above seasonal norms, do not necessarily mean heat waves. Most often, these are heat waves.
The term heat peak is best used during a sudden rise in temperatures, whereas a heat wave corresponds to a longer episode. Météo France judges that a heat wave is in progress when temperatures higher than the monthly average by more than three degrees Celsius are detected, lasting at least three days.
Finally, heat dome is another term used. It settled over almost all of France in May 2022. This meteorological phenomenon can be explained by a large mass of hot air coming from Morocco and Spain, trapped by atmospheric pressure. This usually occurs in summer, but also in spring. It results in scorching heat.
Météo France provides several levels of heatwave vigilance: level 1 (green) corresponds to a “seasonal watch”, level 2 (yellow) to a “heat warning” and level 3 (orange) corresponds to “the ‘heatwave alert’. Finally, level 4 (red), the highest, determines “maximum mobilization”. In summer, it is not uncommon for several departments to be placed on orange or red alert for the heatwave.
Heatwave: what are the temperature records recorded in recent years?
If the heatwave of the summer of 2003 remains in everyone’s memory (and that of 1976 also among older people), France has since experienced other episodes of very high heat. In summer 2019, several absolute temperature records were reached in different cities. According to Météo France data, 50 cities recorded a new record since July 25, 2019. While the summer of 2019 was very hot, certain records were broken during the heatwave of mid-June 2022. During the day scorching heat of Saturday June 18, 2022: 150 municipalities broke a heat record, according to meteorologist Patrick Marlière, interviewed by BFM TV: “We went from 70 cities with monthly records broken, to more than 150 today in France, from the Pyrenees to the Belgian border. The city of Nantes thus broke its record for the month of June with 39.1°C. In the South-West, records of more than 40 degrees were reached: Biarritz with 42.9°, Saint-Jean-de-Luz with 42° or Bordeaux with 40°.
The July 2022 heatwave also recorded temperature records on Monday July 18. Of the 63 records recorded that day, the majority are in the north, west or southwest. We can cite :
- Beaulieu-sur-Layon (49): 42.7°C
- Biscarrosse (40): 42.6°C
- Nantes (44): 42°C
- La Roche-sur-Yon (85): 41.5°C
- Cholet (49): 41.3°C
- Niort (79): 41°C
- Rennes (35): 40.5°C
- Caen (14): 40.1°C
- Dinard (35): 40°C
- Saint-Brieuc (22): 39.7°C
- Noirmoutier (85): 38.7°C
- Lorient (56): 37.6°C
- Brest (29): 39.3
- The island of Yeu (85): 35.9°C
During the heatwave of August 2023, many records were also recorded. Among them :
- 43.2 degrees in Carcassonne on August 23;
- 43 degrees in Nyons on August 23;
- 42.9 degrees in Mirande on August 24;
- 42.7 degrees in Orange on August 22;
- 42.5 degrees in Saint Barthélémy-de-Vals on August 22;
- 42.5 degrees in Montauban and Agen on August 24;
- 42.4 degrees in Toulouse on August 23;
- 42.3 degrees in Nîmes on August 22;
- 42.1 degrees in Narbonne on August 23;
- 41.4 degrees in Lyon on August 24;
- 30.4 at Mont Aigoual on August 23.
The beginning of September was also marked by numerous records with 39°C in Vienne and neighboring departments, 35°C in the south-east notably in Aix-en-Provence, more than 35°C in the Centre-Val departments. -de-Loire, between 32 and 34°C in Brittany and 33°C in Ile-de-France