Good weather in the north, thunderstorms in the south: since mid-May, the northernmost departments in France have enjoyed massive sunshine, coupled with summer temperatures, while the South has been plagued by almost daily thunderstorms.
If the temperatures remain moderate, the situation is remarkable for its duration, the weather having been particularly stable for fifteen days, explains to Point François Jobard, forecaster at Météo-France.
Le Point: What caused the flawless blue skies in the north and the thunderstorms in the south?
François Jobard: Since mid-May, we have had a blocked weather situation. A blocking anticyclone has settled over Northwestern Europe, and an anticyclonic belt has stretched further east towards the Baltic and Germany, while a low pressure axis covers the Mediterranean. It results in stormy rains in Italy, Spain and southern France. The two phenomena are linked, sunny weather in the north and stormy instability in the south of a line from Bordeaux to Lyon, including the Massif Central, the Alps, the Southwest and the Mediterranean. These areas have been subject to almost daily thunderstorms for 15 days.
How long will this last?
This will continue for at least another week, until Friday, June 9th. We have a seven-day limit to forecasting the weather, so it could take longer. The sequence is also quite remarkable for its duration: if the blocking anticyclones lead to situations that change little and can last ten days, this one is set to last three to four weeks in all.
Are we above season averages?
The temperatures are quite high, but we are still far from the records. We are certainly above the average for the season: in Paris, for example, it is currently between 27 and 28 degrees, against 22 degrees on average, but this is not an extreme difference, which is noticeable when we begins to exceed seasonal averages of 10 to 15 degrees.
The current heat is therefore nothing extraordinary, and it continues to be cool at night, so we cannot speak of a heat wave or a heat wave. What is rare is the sequence of days above a certain temperature threshold, coupled with a maximum rate of sunshine.
Like where, for example?
In Strasbourg, 25 degrees have been reached every day since the start of the Pentecost weekend and the sunshine is maximum. These daily 25 degrees could last until June 10. If so, it's going to be a pretty rare streak for this time of year, with such a string of days like this usually not happening until mid-June.
Where is it hottest?
Temperatures are fairly uniform across the whole of France. It is sometimes warmer in the north, which enjoys better sunshine, while the south is cooled by thunderstorms. The highest temperatures are found between Alsace and the Center region. Bourges, Strasbourg and Nevers are close to 29 degrees.
What about drought?
It's been a big concern since last year, because the situation is tough. After the worries of February, the northern regions were well watered in the spring, and the rains that fell were finally quite correct. But there, the situation reverses, with long-lasting sunshine and a northeast wind bringing the humidity down. The soils dry out quickly, and if there is nothing dramatic for the moment, we can arrive on June 10 with soils already very dry for an early summer. However, everything is possible depending on the weather, and there may be abundant rainfall in mid-June, but it should be noted that the soils of the northern regions, which were in a suitable situation in mid-May, are again clearly dry.
In the South, the soil situation is more contrasted: the month of May significantly improved the Paca region, the Var and the Pyrenees, like the region of Nîmes and Languedoc, because the precipitation there was higher than usual , but not all departments are concerned.
What to expect for this summer?
We cannot predict so early how the summer will unfold. Seasonal forecasts do not allow us to say. The only thing certain is that we can expect to have a warmer quarter than normal, since that is what global warming is driving.
