The mercury will climb on the Hexagon. Summer temperatures are expected from Monday May 9 in France, during the so-called ice saints period. What is this phenomenon due to? How long will it last? Is it part of the global trend of global warming? Patrick Galois, forecaster at Météo France, answers questions from franceinfo.
Franceinfo: The sun and the heat will settle in the country next week. Is this normal at this time of year?
Patrick Galois: Ot is now coming to the end of spring, it is quite a classic phenomenon to have these first summer flushes. There is a thrust from the Azores anticyclone, which will position itself over a large part of the European continent, associated with rising warm air. These anticyclonic conditions at high altitude result in dry and hot weather.
What exactly can we expect for the week?
A first push of warm air is expected on Monday, Tuesday and Wednesday. The mercury should reach 28 ° C in Paris, eight degrees above seasonal norms, and peaks at 30 ° C in the South, even in the center of the country. Thursday and Friday, the air will be a little cooler, with a small influx of maritime air linked to a westerly wind, which will lower temperatures north of the Loire. This may result in some thundery showers. This small degradation will be short-lived since we will find high pressure conditions next weekend over the whole of France.
Can we speak of a “heat wave” and can this episode last?
We are talking about “heat wave” during episodes which are accompanied by a heat wave during the summer period, starting in June. In these cases, temperatures can approach 20°C at night, which is not the case in May. No consequences on health are therefore to be feared. We can rather speak of a remarkable heat episode for the season, which can be quite long-lasting. But we do not yet have all the elements to know if these temperatures will continue the following week.
Is it possible to see a link with global warming?
It is difficult to characterize an event whose duration we do not know. This kind of heat stroke has already been observed in the past at this time. In Paris, the heat record for the month of May is 35°C in 1944. And in 1998, the ice saints – from May 11 to 13 – saw temperatures reach or exceed 30°C in the capital and in Lille. But it is true that this kind of episode can happen earlier in the year and have a more lasting aspect, in connection with global warming.
“Hot days are more frequent throughout the year and May is on average warmer than fifty years ago, although high variability may mask this long-term trend.”
Patrick Galois, forecaster at Météo Franceat franceinfo
Will this arrival of hot air make the drought worse?
We are going towards days favoring the progressive drying of the soil, which is much drier than normal in certain regions, the South-East in particular but also the Nord-Pas-de-Calais. Ideally, there should be alternating periods of good weather and disturbances. But when we move towards summer, this is generally not the expected scenario, even if the seasonal forecasts for the summer period will only be available at the end of May-beginning of June. The situation therefore needs to be monitored.