As at the beginning of each month, we offer you a new climatological report. Place now in the mapped balance sheet of the WEATHER SUMMER 2023 in terms of temperature, rainfall and sunshine on a panel of 73 stations*. As a reminder, the meteorological spring includes the months of June, July and August. The anomalies presented are calculated from the climatic averages of the reference period 1991-2020.
The meteorological summer is now behind us. And if it seemed for some quite fresh, it is not so: this summer 2023 has become the 4th hottest observed in France since at least 1900with a +1.4°C anomaly compared to the 1991-2020 average!
With a thermal indicator of 21.8°C, it is placed behind thehistorical summer 2003 (+2.7°C – 23.1°C), followed by summer 2022 (+2.3°C – 22.7°C) and finally summer 2018 (+1.5°C – 21.9°C). A gloomy feeling therefore quite biased because last summer was almost a record!
National thermal indicator for meteorological summer (June-July-August) since 1900 – Meteo France
A summer that started with lasting heat: June had become the 2nd hottest never recorded with 29 out of 30 days above averages. However, July was more mixedwith a persistent heat in the south while temperatures remained just about average in the North. A situation similar in august (very hot in the South of the Loire, right in the middle in the North) with which more is a striking contrast according to the periods (very cool at the beginning of the month, a remarkable heat wave passed on August 15 and finally a return to cool weather for the very last days). A summer of which we will keep in mind this historic heat wave at the end of Augustthe most intense also late in the season with several hundred absolute records broken and up to 43 or even 44°C in Occitania (>>).
Here is the thermal summary of the three months of the meteorological summer of 2023:
JUNE 2023: +2.5°C (>>)
JULY 2023: +0.8°C (>>)
AUGUST 2023: +0.9°C (>>)
National thermal indicator for meteorological summer 2023 (June-July-August) and deviations from the 1991-2020 average – Meteo France
In the end, despite this so-called “fresh” or even “rotten” impression for some people, this does not in any way affect the temperatures, since all cities experienced a warmer than average summer weather ! Moreover, except along the coasts of the English Channel, the anomaly rises everywhere above +1°C (minimum of +0.5°C in Lorient+0.7°C in Cherbourg, +0.8°C in Brest and Caen, +0.9°C in Le Touquet).
3/4 of the country even got a particularly hot summer overall, with surpluses reaching the +1.5°C to +2°C from Midi-Toulousain to Alsace, via the Massif-Central in particular, where the surpluses are the highest (+2.0°C in Clermont-Ferrand, and a maximum on our panel of +2.1°C at Le Puy-en-Velay). For the capital, the station of Paris-Montsouris loops this summer with an anomaly of +1.3°C.
For precipitation, the results are more hesitant and contrasting. National statistics on our station panel, fairly close to seasonal averages (+3% surplus) indeed hidessignificant disparities depending on the month, and depending on the region. The month of June was notably marked by abnormally unstable and excessively stormy conditions over the entire southern half of the country (almost daily thunderstorms, in 2nd place for the worst lightning strikes in June since 1997) while the anticyclonic conditions prevailed in the North. A situation which was noticeably reversed in July then Augustwith many days sometimes well rainy and gloomy in the northern regionswhile the southern cities found a time much drier.
Ultimately, here is the rainfall summary for the three months of the meteorological summer of 2023:
JUNE 2023: +8% (>>)
JULY 2023: -6% (>>)
AUGUST 2023: 0% (>>)
The frequent rainy spells in July and August in the northern regions clearly took over from the dry conditions in June. The first indication of a summer with a rotten feeling north of the Seine therefore comes from this humidity with surpluses sometimes ranging between +20 et +40% (+23% in Paris, +32% in Alençon, +33% in Troyes, up to +43% in Charleville-Mézières). Excess rainfall sometimes observed in the South, more heterogeneously in Occitania and along the Mediterraneanbecause of thunderstorms in junen or a brief rainy-stormy episode at the end of August (+34% in Ajaccio, +45% in Carcassonne, +50% in Marseille-Marignane).
On the deficit side, part of theAtlantic arc, the south of the Center region, the Côte d’Azur, but also Auvergne and Rhône-Alpes were much less served than a “normal” summer, with anomalies ranging from -15 to -30% depending on the town (-23% in Châteauroux, -25% in Mont-de-Marsan and Bourg-Saint-Maurice, -29% in Cognac, -30% in Nice).
Translated in terms of accumulations, the Mediterranean regions, usually the driest, are no exception to the rule with less than 100mm observed on average, even sometimes less than 50mm in three months (47mm in Nice and Montpellier, 28mm in Hyeres). The Charentes or part of the Pays-de-la-Loire did not collect significant rainfall this summer, painfully exceeding this bar of 100mm (111mm in La Roche-sur-Yon, 113mm in Cognac, 119mm in Nantes) .
Conversely, the rains appeared more abundant in the Pyrenees, Massif-Central, Finistère, and all regions north of the Seine where the 200mm have been crossed (207mm in Paris, 244mm in Limoges, 257mm in Abbeville, 266mm in St-Girons and Besançon, and a maxi on our panel of 306mm in Charleville-Mézières).
Just as for rainfall, the sunshine balance requires an in-depth look according to the regions and according to the months. Indeed, the balance sheet for this summer as a whole, although very slightly surplus (+4%), does not reflect this reality everywhere. Because it is the month of June which weighed heavily in this balance sheetwith conditions historically sunny on the northern half (sunniest month in history for several cities with 300 to 350 cumulative hours and surpluses of +40 to +60%), while the South had to face the outbreak of many thunderstorms (deficits from -10 to -20%). The months of July, and especially August (excessively gray in the North with -20 to -30%) have not made it possible to make up for these surpluses, but they contribute very strongly (in addition to the humidity) to this very gloomy feeling in the North of the Loire.
Here is the sunshine summary for the three months of meteorological summer 2023:
JUNE 2023: +20% (>>)
JULY 2023: -2% (>>)
AUGUST 2023: -6%(>>)
Despite this very cloudy month of August, the northern regions therefore end on a excess sunshine from +5 to +15% over the whole of this meteorological summer, largely carried by this radiant month of June (+10% in Paris, up to +16% in the cities of Colmar, Nantes, Rouen and Le Touquet). In cities in the South, the June deficit was largely made up forwith a summer season coming to an end more or less in the averages of the season from Poitou to Corsica, passing through the north of Occitanie and the PACA region. On the side of the regions ending on a deficitwe had to go to the tip of the Cotentin (-7% in Cherbourg), in the Limousin (-4% in Limoges), and especially on the South of Aquitaine and along the Pyrenean barrier (-6% in St-Girons, -9% in Bordeaux, -11% in Tarbees).
In the end the sun shone less than 700 cumulative hours over the whole of the three months of this meteorological summer in towns near the Channel coastsometimes even dropping under 600h in northern Brittany (573h in Saint-Brieuc, 534 hours in Brest). The Pyrenean Piedmont is also one of the least luminous sectors of this summer with only 613h in Biarritz, 575h in Saint-Girons and 546 hours in Tarbes.
If we reach 750 to 800 hours on average from the Centre-West to the North-East, or even 800 to 850 hours in the South of the Massif-Central and in Rhône-Alpes, it is as if systematically going towards the Southeast where we find the most generous sunshine. From Languedoc to Provence and Corsica, the sun shone for more than 900 hours in total, with even a peak beyond 1000 hours for two cities in our panel: Marseille-Marignane (1047 hours) and Ajaccio (1064 hours).
Summary:
* PANEL OF 73 STATIONS
Temperature – rainfall – sunshine:
Agen, Ajaccio, Albi, Alençon, Angers, Aurillac, Beauvais, Bergerac, Besançon, Biarritz, Bordeaux, Bourges, Bourg-Saint-Maurice, Brest, Brive, Caen, Calais, Carcassonne, Charleville-Mézières, Chartres, Château-Arnoux- Saint-Auban, Châteauroux, Clermont-Ferrand, Cognac, Colmar, Dijon, Embrun, La-Roche-sur-Yon, Langres, Le Mans, Le-Puy-en-Velay, Le Touquet, Limoges, Lorient, Luxeuil, Lyon- Bron, Mâcon, Marseille-Marignane, Melun, Millau, Mont-de-Marsan, Montélimar, Montpellier, Nancy-Essey, Nantes, Nevers, Nice, Nîmes-Courbessac, Niort, Orléans, Paris-Montsouris, Perpignan, Poitiers, Rennes, Saint-Brieuc, Saint-Etienne, Saint-Dizier, Saint-Geoirs (Grenoble), Saint-Girons, Strasbourg, Tarbes, Toulouse-Blagnac, Tours, Troyes.
Temperature – rainfall (lack of sunshine data):
Abbeville, Bastia, Hyères, Lille, Metz, Romorantin, Saint-Quentin.
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