An endless furnace. This is the memory that the summer of 2022 will leave, for many, with the French in general, and with the people of Lyon in particular. Across the country, the mercury reached an average of 22.67°C in June, July and August, compared to 23.10°C during the summer of 2003. However, in Lyon, the thermometer exceeded 30° C for 52 cumulative days. New record ? Not necessarily.
“In Lyon, we had the second hottest summer since the beginning of the records of the Lyon-Bron station, so since 1921”, confirms Romain Weber, from Lyon weather, which offers precise forecasts for companies, communities and individuals. “But 2003 remains well above in terms of heat: this year, Lyon recorded a day at 38.9°C, and 2-3 days at 38°C, against 15 days between 38°C and 40°C in 2003,” he says.
Powerless thunderstorms to cool and water
For the meteorologist, it is above all the drought that has been “exceptional” this year. After an abnormally dry winter and spring, the summer got worse: “In Lyon, there was almost 0 millimeters of precipitation in July,” he notes. “We had a few storms, but they do more damage than anything else. We are still 150 millimeters behind, which we are far from being able to catch up. »
If it is so hot and dry in the capital of Gaul, it is largely due to its topography. Located at the exit of the Rhone Valley, the city is collected “in a kind of basin, quite low in altitude, where the air overheats”, specifies Romain Weber. “The Mediterranean climate tends to rise gradually, so we have more and more Mediterranean influence on the whole of the Lyon region. The Monts du Lyonnais and the Monts du Beaujolais will also have an influence on the Lyon climate, “but more in terms of precipitation than in terms of heat”, he adds.
Air conditioning, the only short-term solution to protect the most vulnerable
While the first refreshments in September are still awaited, the meteorologist does not rule out… a new heat wave. “Not a heat wave”, he reassures, “but see this stormy week where we stay at 30°C, whereas in this season, at the beginning of September, we should be at 14°C in the morning and at 25°C the day. However, last night, we were at 22 ° C and we are still going up to 31 ° C this Tuesday… ”
It is this continuity in the heat – almost four months without any real respite – which worries and exasperates. How to protect against it? “Individually, we can’t do much,” admits Romain Weber, who recommends greening the city, a long-term solution already implemented by the ecological municipality, on the condition of using vegetation that requires little effort. ‘water. But in the short term?
“Unfortunately, it would be the air conditioning,” says the meteorologist, while tempering: “the air conditioning saves lives. The 2003 heat wave killed around 20,000 people. If we had experienced the same heat wave this year, we might have had 4 times fewer victims thanks to that”. The communes, they, will have to continue to act quickly: a tree with fast growth, like the lime tree or the eucalyptus, puts about twenty years to reach its adult size. And to grow, it will need water…