HEAT 2023. After a scorching month of July in the south of France and a Europe in the grip of the heat, the French fear the rest of the summer. What about the forecast for August and possible heat waves ahead? Here’s what you need to know.
[Updated August 10, 2023 at 4:00 p.m.] Good news for vacationers, a period of high heat is beginning in France. The Weather Channel estimated the temperatures “will remain permanently above normal, at least for the next 10 days, with disparities between regions nevertheless.” The conditions necessary to trigger a heatwave alert are rigorously defined, which makes long-term forecasts tricky. However, the Rhône Valley and Provence are the areas most likely to soon be affected by a heat wave. Drôme and Ardèche are the first departments to be affected in August, having been placed on heatwave yellow alert.
The south-east of France experienced a very hot month of July with a fortnight’s heat wave. Météo-France had placed 10 departments on heat wave vigilance on July 9. This episode of very hot weather ended on July 25 to give way to rain and thunderstorms. During this heatwave episode, many records were broken in the Mediterranean, with 49 degrees in Algiers and Tunis. In Spain, “Spanish Catalonia recorded 45°C near Figuères, a record for this province” according to the Weather Channel. In France, it is the city of Castirla in Corsica which recorded a temperature record with 42.8 degrees.
But what about the month of August? Should we expect hot weather again? the forecasters of the Weather Channel announce “a generally summery month of August, especially in the south”. Here is the forecast from The Weather Channel:
As a reminder, we speak of a heat wave when these four characteristics are combined:
On June 8, 2023, the government announced the various actions implemented as part of its heat wave plan to protect the population during intense heat waves.
Heat wave and heat wave are two different things. To speak of a heat wave, the temperatures must be five degrees higher than normal for the season, day and night, and this for at least three days and three nights. The heat wave temperature threshold therefore differs according to the departments and regions. Heat waves most often occur in France in July and August. We must be vigilant from the month of June. High temperatures, even above seasonal norms, do not necessarily mean a heat wave. Most often, these are heat waves.
The term heat peak is more to be used during a sudden rise in temperature, whereas a heat wave corresponds to a longer episode. Météo France judges that a heat wave is in progress when temperatures above the monthly average are detected by more than three degrees Celsius, for at least three days.
Finally, heat dome is another term used. It settled over almost all of France in May 2022. This meteorological phenomenon is explained by a large mass of hot air 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 heat wave vigilance: level 1 (green) corresponds to a “seasonal watch”, level 2 (yellow) to a “heat warning” and it is level 3 (orange) which corresponds to “the ‘heat wave 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 heat wave.
If the heat wave of the summer of 2003 remains in all memories (and that of 1976 also among the old), France has since experienced other episodes of very hot weather. In summer 2019, several absolute temperature records were reached in different cities. According to data from Météo France, 50 cities had set a new record since July 25, 2019. While the summer of 2019 had been very hot, some records were broken during the heat wave of mid-June 2022. During the day heat wave of Saturday June 18, 2022: 150 municipalities broke a heat record, according to meteorologist Patrick Marlière, interviewed by BFM TV: “We went from 70 towns with broken monthly records, 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 at over 40 degrees have been reached: Biarritz with 42.9°, Saint-Jean-de-Luz with 42° or Bordeaux with 40°.
The July 2022 heat wave also set 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 :
