Despite heavy rains and a lack of sunshine compared to the summer of 2023, temperatures were higher than the averages calculated for the period 1970-2000.
The impression of a classic, even gloomy summer? Metropolitan France has had a wet summer and the sun has been more timid than usual. But despite this lack of sunshine, the average temperature from June 1 to August 31 was 21.09°C, or 1.75°C above that calculated over the period 1971-2000, particularly due to a warmer than normal August. In total, 73 days out of 92 were warmer than normal and two heat waves hit the territory. A phenomenon amplified by global warming, caused by human activity. Franceinfo draws up the weather report for summer 2024.
Torrential rains in July
Rainfall has been very uneven this summer. It was heavier in June than usual, with rainfall “20% surplus” compared to the normal calculated between 1991 and 2020, but 25% below the average for the month of August, according to the Météo-France summer bulletin consulted by franceinfo.
While rainfall was within seasonal norms in July, in some places, “Monthly totals exceeded 100 mm following torrential rains during violent stormsrecalls the forecasting institute (PDF document). They reached one and a half to more than twice the normal in places, notably from the Paris Basin to Champagne-Ardenne and the north of Lorraine.”
These storms caused flooding, mudslides and floods, such as in the hamlet of La Bérarde, in Isère, and in the Vésubie valley, in the Alpes-Maritimes. “The higher the temperatures, the greater the risk of intense precipitation. The higher the air temperature, the more moisture it can hold. And so when it rains, we have a greater chance of it ‘precipitating’ strong”that is to say that the precipitations are more intense, says Antoine Nicault, ecologist and coordinator of the regional group of experts on climate in the South Provence-Alpes-Côte d’Azur region (Grec-Sud).
While the Paris Basin and the Centre were very wet, the South-East received almost no rain. The Provence-Alpes-Côte-d’Azur region recorded a precipitation deficit of 21% in the summer of 2024 compared to seasonal norms. The region was nevertheless able to escape drought thanks to the spring rains, which “allowed to recharge the water tables sufficiently”says Antoine Nicault.
Warmer days than before 2000
The average temperature for the summer of 2024 was 21.09°C, which is 1.75°C above the average temperature for the period 1971-2000. As can be seen from this graph, 73 days of the summer were warmer than the average temperature measured between 1971 and 2000, only one day was within the norms and 18 were colder. “Temperatures in June and much of July were close to seasonal norms.estimates climatologist Serge Zaka. But in August, they are in surplus.”
“The summer of 2024 will be different from previous summers, which have been extremely dry and hot, especially in the last two years”continues Serge Zaka. In comparison, it was an average of 21.8°C during the 2023 summer season and 22.7°C in 2022. “So we can have a false impression that this year’s summer was cool and rainy. But if we compare it to before 2000, it was a hot summer.”assures the climatologist.
The same observation was made by Météo-France, this time regarding night-time temperatures. “Nearly 70% of France experienced at least one so-called ‘tropical’ night during the summer, with a nighttime temperature above 20°C. This is a proportion of the territory broadly similar to summers in the 21st century, but much higher than that of the 20th.“, explains the institute in its report.
As this chart shows, the summer of 2024 is the ninth warmest since 1940, and all summers before 2000 have been cooler than it. “We remain in a context of global warming, with an increase in general temperatures”summarizes Antoine Nicault.
Shorter heat waves, but 40°C exceeded several times
France was hit by two heat waves: one from July 30 to August 2, and another from August 6 to 13. Unlike the summer of 2022, “The heat waves were shorter than the two previous summers. That’s why they didn’t push the average up muchexplains Serge Zaka. We were very lucky, because the rest of Europe is experiencing exceptional thermal excess.”he points out. While the continent recorded its second hottest summer, “temperatures were most above average in southern and eastern Europe”the Copernicus Observatory said.
The phenomenon, although rare in the past, has become frequent. “In France, before 1989, we observed a heat wave on average once every five years. Since 2000, years without a heat wave have been rare.”recalls Météo-France on its website. “We still have interannual climate variabilityadds Antoine Nicault. But it’s no longer: ‘we have a heat wave or we don’t have one’, it’s: ‘they are more or less long and intense'”.
Even though the heatwaves were shorter, heat peaks were observed and the 40°C mark, exceptional before 2000, was exceeded several times. For example, the thermometer reached 40.3°C in Moulès-et-Baucels, in Hérault, 41.1°C in Biscarosse and 41.5°C in Hossegor (Landes). “It’s a threshold that we didn’t look at too much before because it was episodic. We are becoming more and more interested in it, because it is a good marker of global warming.”explained Matthieu Sorel, climatologist at Météo France, to franceinfo in July.
Southeast less still warmer than normal
The summer was marked by regional disparities. The South-East recorded excess heat (+2.5°C in Nice), compared to the period 1970-2000, greater than Brittany (+0.3°C in Brest) for example. The Provence-Alpes-Côte-d’Azur region experienced its sixth hottest summer since 1947, according to Météo-France.
Nice (Alpes-Maritimes) was particularly crushed by the heat and at the end of the summer was 2.5°C above the average temperature (1971-2000), after a summer of 2023 at +2.7°C. “July-August was the second hottest period” for this city, which “has been experiencing uninterrupted tropical nights since the 6th July”, according to the Météo-France report. “We had a few more cloudy days which lower the temperatures during the day, but keep the heat at night,” explains Christine Berne, climatologist at the forecasting institute.
Note that during the summers In 2022 and 2023, some regions have warmed as much, or even more, than the South-East. In 2023, for example, Clermont-Ferrand was +3.2°C compared to the 1971-2000 average and Dijon +2.9°C, according to Météo-France data.
The Mediterranean Sea is overheating
For the second year in a row, Mediterranean Sea temperatures have broken records this summer. On August 15, the daily median surface temperature of the Mediterranean Sea reached an all-time high of 28.47°C, according to Copernicus Marine. “Since August 6, sea surface temperatures in the region have been above 28°C, marking the most prolonged period above this threshold”the European X Observatory specified on this occasion.
For two successive summers, the Mediterranean will have been warmer than during the exceptionally hot summer of 2003, when a daily median of 28.25°C was measured. “These extreme temperatures represent global warming very well,” Antoine Nicault slips.
These marine heatwaves are becoming more and more frequent due to rising temperatures, because the seas and oceans absorb 90% of the excess heat, according to the UN. With harmful consequences on biodiversity, such as coral bleaching, disruption of the food chain or a drop in reproduction.
Since the 19th century, the average temperature of the Earth has warmed by 1.1°C. Scientists have established with certainty that this increase is due to human activities, consumers of fossil fuels (coal, oil and gas). This warming, unprecedented in its speed, threatens the future of our societies and biodiversity. But solutions – renewable energies, moderation, reduction of meat consumption – exist. Discover our answers to your questions on the climate crisis.