As at the start of each month, we offer you a climatological report of the past month. So let’s take a look at the mapped balance sheet for the month ofOCTOBER 2023 in terms of temperature, rainfall and sunshine over a panel of 73 stations*. The statistics are calculated under the official climate average for the period 1991-2020.
The series is endless and nothing seems to be able to stop it. With a warm anomaly of +2.6°C nationally, October 2023 has become the 21st consecutive month without falling below average of the season.
After an already historic month of September (the hottest ever measured >>), October followed the same path by placing itself in second place, just behind last year’s record… (+3.4°C in October 2022) but a few hundredths of a degree beyond October 2001 (also rounded to +2.6°C).
Average national heat indicator in October since 1946 – Infoclimat
The first half of this month of October had also been historically summery and hot (review the results of this exceptional sequence >>) with temperatures that had nothing to envy of summer: from October 1 to 13, maximum temperatures were +6.7°C above average of the season. Frequently exceeding 30°C, hundreds of monthly records have been broken, and even one new national heat record for the month of October (35.8°C in the Pyrénées-Atlantiques in Navarrenx, October 2).
If we very stealthily fell below average on the days of October 15 and 16, mild weather quickly returned to the entire country for the second half of the month thanks to a predominantly oceanic flow (much less hot in the afternoon but often very mild mornings).
Daily temperature anomaly in October 2023 in France – deviation from the 1991-2020 average – Infoclimat
With such gentleness, all metropolitan meteorological stations observed a thermal surplus of at least +1.5°C (whether on our panel or on the thousand Météo-France stations). Indeed, western Brittany (+1.5°C in Lannion (Côtes-d’Amor), Ouessant (Finistère) and Brennilis (Finistère)), Cotentin (+1.7°C in Cherbourg) or even the coast Varois (+1.7°C in Hyères) are the sectors with the least significant anomalies.
An anomaly which even exceeds +3°C from the Pyrenees to the south of Alsace, passing through the Massif-Central, Rhône-Alpes and Franche-Comté. On our panel, the excesses rise to +3.5°C in Tarbes and Saint-Etienne, +3.6°C in Clermont-Ferrand and +3.7°C in Langres. On the secondary network, some cities even exceed +4°C : up to +4.3°C in Revel (Haute-Garonne) and +4.6°C in Chazelles-sur-Lyon (Loire).
This is finally some good news, October 2023 finally marks the return of the rains. On our panel of stations, the rainfall balance is in fact excess of around +36%.
And yet, this month did not start under good auspices, with anticyclonic, summery and particularly dry weather across the whole of France. But from October 17a major upheaval of the action centers contributed to the return of humidity in all regions without exception, between a vigorous oceanic westerly flow carrying active and regular fronts on one side, and several Cévennes and Mediterranean episodes in the South-Eastern quarter (with red vigilance over the Alpes-Maritimes on the 20th). October >>). Finally, while 4mm fell overall across France from September 22 to October 16, this value climbs to 116mm fell over the period from October 17 to 31.
The rains in the second half of the month were therefore more than enough to reach and even far exceed monthly rainfall averages in most regions. In some cities in the Northeast, but especially in New Aquitaine, the accumulations are sometimes even twice the average (+102% in Nancy, +103% in Bergerac, +107% in Limoges, +118% in Niort, +125% in Bordeaux, +126% in Langres, and even +176% in Villiers (Charente-Maritime) on the secondary network). If this does not appear,The Cévenol sector as well as the south of the Alps was also affected by heavy rains (often 2x normal) with an anomaly reaching +189% in Arvieux (Hautes-Alpes).
However, some sectors were not served. This is the case on the Côtes d’Armor (-29% in Saint-Brieuc), in Limagne and South of Massif-Central (-18% in Clermont-Ferrand and -13% in Puy-en-Velay). If the hinterland and the relief have been affected by rainy episodes, the entire Mediterranean coast was not, however, watered with significant deficits, mainly on the eastern coast of Corsica (-93% in Bastia, -92% in Solenzara) as well as on Roussillon (-81% in Perpignan, -93% in Serralongue).
In terms of accumulations, these frequently exceed 100mm on the country, falling almost entirely from October 17. 150mm is even reached in many towns in New Aquitaine, in Cotentin, Pas-de-Calais, the Alps, in Franche-Comté and on the Cévenole barrier: for our panel, we reach 181mm in La Roche-sur -Yon, 184mm in Le Touquet, 185mm in Grenoble-St-Geoirs, 188mm in Bordeaux, 189mm in Langres, 193mm in Niort and 195mm in Limoges. On the Cévennesthese accumulations are in places greater than 400mmwith a tip 588mm on the La Souche side (Ardèche).
In the Massif-Central, in Corsica, on the Provençal and Languedoc coast, but also in Midi-Toulousain and Roussillon, these rainfall totals are much lower, failing to reach 50mm. In places, the accumulations remain insignificant, with 17mm in Carcassonne, 15mm in Perpignan, 9mm in Bastia and even 6mm in Vinça (Pyrénées-Orientales) on the secondary network.
Despite the hustle and bustle at the end of the month, the sunshine was mainly brought by a first half excessively summery and therefore bright. The results on a national scale are then excess of +22% on our range of stations.
It is in the South-East quarter where we note the smallest differences, due tofairly frequent maritime entries from mid-October (leading to the Mediterranean episodes): +3% in Nîmes, just average in Montpellier, Saint-Auban and Bourg-Saint-Maurice, and even a deficit in Embrun (-12%), the only city in the panel below average. Finistère (+1% in Brest) and Pas-de-Calais (+5% in Le Touquet) are also close to the monthly averages.
Everywhere else, the excess sunshine is notable or even remarkable thanks to this first half of the month. In the regions from northern Brittany to Alsace, this sun was omnipresent, with +30 to +40% anomaly on average : this increases to +41% in St-Brieuc and Langres, +43% in Dijon, and even +49% in Mâcon (maximum panel).
In terms of total duration, this sunshine was on average between 160 and 190 hours in all cities located south of the Loireand even more than 200 hours in Provence, Côte d’Azur and Corsica (222 hours in Ajaccio221 hours in Marignane, 215 hours in Bastia and on Ile-du-Levant (Var)).
On the side of the lowest durations, we find them on the north of the Alps, north of the Seine as well as on the Finistère with sometimes less than 130 or even 120 hours cumulative: the national minimums are 111 hours in Charleville-Mézières, 110 hours in Brest but also for Villard-de-Lans (Isère).
Summary:
* PANEL OF 73 STATIONS
Temperature – rainfall – sunshine:
Agen, Ajaccio, Albi, Alençon, Angers, Aurillac, Bastia, Beauvais, Bergerac, Besançon, Biarritz, Bordeaux, Bourg-Saint-Maurice, Bourges, Brest, Brive, Caen, Carcassonne, Charleville-Mézières, Chartres, Châteauroux, Cherbourg, 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-Auban, Saint-Geoirs (Grenoble), Saint-Girons, Saint-Quentin, Strasbourg, Rouen, Tarbes, Toulouse-Blagnac, Tours, Troyes.
Temperature – rainfall (partial or total absence of sunshine data):
Abbeville, Calais, Lille, Metz, Hyères, Romorantin.
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