This Wednesday turned out to be particularly summery. The culmination of a sweltering week, the day was marked by a few thermometer records with temperatures locally reaching 30°C in the east of the country. Throughout the territory, the sun shone and this taste of summer is not over. But does this heat wave presage a scorching summer? 20 minutes make the point.
Difficult to predict rain or shine long in advance
We must first separate two things: precise predictions with given temperatures and longer-term weather estimates. Predicting that it will be 27°C in Toulouse on a specific date cannot be done too far in advance. “We can’t go further than ten days”, explains Fabio d’Andrea, climatologist at the ENS Dynamic Meteorology Laboratory.
However, there are average forecasts for the next three months. Météo-France thus predicts that for the months of May, June and July, the weather will probably be hotter and drier than usual. Across France, the meteorological institute estimates a 50% probability that temperatures will be higher than normal for the season, 25% that they will be consistent and 25% colder.
A “classic” but “early” heat wave
“It’s too early: we can’t make a link between what’s happening now and this summer,” confirms Matthieu Sorel, climatologist at Météo-France. Forecasts are therefore uncertain, even if a scenario is emerging. Moreover, this heat wave is “a fairly classic configuration. We have already had hot episodes during the month of May”, underlines the expert, citing 2017 and 2009 in particular. was quite cool.
The current episode is however “remarkable for its precocity, the hot episodes of the other years were rather at the end of May”, remarks Matthieu Sorel. However, he did not surprise the weather experts who had “predicted” his arrival in the country a few days before, recalls Fabio d’Andrea. In addition to particularly hot weather, climate experts have noted a severe drought for the territory: an important criterion when talking about heat waves.
Drought and heat, great friends
Over the next three months, “we should have a deficit of rain”, underlines the climatologist of Météo-France. The country is already in the grip of drought. On Monday, the FNSEA, the majority agricultural union, warned: “No region is spared. Every day that passes, we see soils cracking. In addition to the lack of water for crops, the drought could accentuate an episode of high heat this summer.
“It’s a vicious circle: the evaporation of water from the ground has a cooling effect. If we find ourselves in a drought situation before a heat wave, there is no cooling effect,” explains ENS climatologist Fabio d’Andrea. If meteorologists cannot predict a heat wave for this summer, “under current conditions, if it happens, it could be more serious”, he underlines.
“Climate change is here”
And the situation is unfortunately not likely to improve. “In the future, we expect more and more heat waves and earlier and earlier in the year,” recalls Fabio d’Andrea. Because “if we cannot say that this heat wave is specifically a sign of global warming, heat waves of this type are consistent with climate change”.
“Climate change is there behind, for the same episode, we will be warmer,” adds Matthieu Sorel. And while the United Nations World Meteorological Organization (WMO) has announced that we have a one in two chance that the 1.5°C threshold will be temporarily crossed within five years, the overheating of the blue planet seems far from over.