December 1st marks the official start of meteorological winter in France, but it is important to understand that this date does not necessarily mean immediate cold. Indeed, calendar winter and meteorological winter do not always coincide perfectly, and it is useful to distinguish these two concepts to better understand what awaits you in the months to come.
Why this difference between meteorological and calendar winter?
Calendar and meteorological winter © The Weather Channel
The difference between winter meteorological and winter calendar lies primarily in how these seasons are defined and how they are used for practical purposes.
Calendar winter corresponds to the traditional definition of seasons, as recorded in the calendar. It starts around the 20 Decemberduring the solstice d’hiverand ends towards the 20 mars. This is the time when we celebrate Christmas and New Year and when the length of daylight is shortest. This period coincides with the angle of the Earth in relation to the Sun, which explains the shortest days and longest nights, characteristic of winter.
Meteorological winter commence December 1st and ends on February 28 or 29 (depending on the year), covering the three months of December, January and February. This definition is used by climatologists and meteorologists for practical reasons, as it simplifies the analysis of climate trends by grouping the months of the same season into fixed periods. Indeed, fixed periods of three months (meteorological winter) are more suitable for collecting climatic data and analyzing long-term trends. This division makes it possible to better compare the seasons with each other.
Great climatic differences in France
Winter in France is characterized by great climatic diversity, influenced by geography and atmospheric conditions.
On average, daytime temperatures in winter range between 3°C and 10°C across most of the country, with significant regional variations. The national winter average is +5.4°C. But since the start of our century, this average has often been close to 7°C, the mildest having been 2019-2020. The five coldest winters since 1900 in France occurred between 1928 and 1963, with 1962-1963 being the most severe.
THE types of weather in winter of course depend on the direction of the winds and the origin of the air masses. In France, the dominant winds come from the southwest, explaining the oceanic character of our climate.
Temperatures
In the north of France, temperatures are lower, sometimes falling below zero. January is the coldest month of the year.
In the south of France, particularly along the Côte d'Azur and in the southwest, average temperatures remain higher, between 7°C and 10°C, with less intense and less lasting cold periods. .
The cold record in France was recorded in Mouthe, in Doubs, with -36.7°C in January 1968. On the other hand, in winter, records for mildness can also be observed, particularly in Corsica, with 22 .4° C in Ajaccio in January 1997.
With global warming, winters are getting significantly warmer in France, with an acceleration since 2010. The number of days of frost is decreasing, especially in cities, linked to “urban heat islands”. The last cold winters were 2005, 2009 and 2012.
The number of days of frost is constantly decreasing in France. Here, Nancy © The Weather Channel
Precipitation:
Winter is a wet season, with averages of 80 to 100 mm per month in lowland and coastal regions. This rain is often more abundant on the Atlantic coast, where it can exceed 150 mm per month in December and January. Floods are one of the hazards of our winters in mainland France, like those of last year in the North and Pas-de-Calais.
The Alps and the Pyrenees receive significant snowfall, which can accumulate several meters at altitude, favoring winter sports activities. However, for around fifteen years, snow cover has become very uneven on our mountains, and often absent. sous 1500 m d’altitude.
Snow :
Snow is more common in mountainous areas (Alps, Massif Central, Pyrenees), where significant falls are common between December and March. On the other hand, snow remains rare, or even non-existent, on the Atlantic coasts and in the Mediterranean regions, where winter is milder.
Periods of freezing rain are possible in central and eastern regions of France, particularly when a disturbance from the west hits air with temperatures near freezing.
Just like the number of frost days, snow days are decreasing in our country, et white Christmases are becoming rarer and rarer.
Evolution of the number of days of snow in France since 1950 © The Weather Channel
Winds and storms:
Storms in France mainly occur in winter © The Weather Channel
Winter in France is the season of storms, particularly on the Atlantic coasts. Violent winds blow frequently, especially in January and February, with gusts that can reach 100 to 130 km/h in certain regions.
Storms like those of December 1999, Xynthia (2010) et Klaus (2009) showed that winds in winter can cause considerable damage.
Winter in France, whether meteorological or calendar, plunges us into a period of transition marked by colder temperatures, sometimes snowy landscapes, but also sometimes difficult weather conditions. December 1st not only announces the start of this season, but also the promise of cocooning moments at home, preparations for the end of year celebrations, and for some, a vacation in the mountains. But it also reminds us of the need to prepare for changing climatic conditions, whether it is snow on the roads or unexpected temperature drops, especially in a context of high energy prices.
