Four departments are going through heat wave orange vigilance this Sunday. For a forecaster from Météo France, this heat wave will last several days with peaks around 37 degrees.
While Ain, Isère, Rhône and Alpes-Maritimes were placed on heat wave orange vigilance this Friday, Claire Chanal, forecaster at Météo France, explains, on franceinfo, that “several consecutive days of intense heat” are planned in these four departments.“They will potentially have the highest temperatures on Sunday, around 36 or 37 degrees. The hottest temperatures are expected from Sunday and Monday between Provence and the Rhone Valley. It will then be necessary to monitor the following days how this evolves .”
franceinfo: What does a heat wave orange alert mean?
Claire Chanel: An orange alert means that we will have several consecutive days of intense heat, according to criteria defined by Météo France and Public Health France. According to the departments, there are heat thresholds that are defined, with a threshold on the minimum and maximum temperatures.
For example, in the Gard, it is quite possible to have temperatures above 20 degrees at night and above 35 degrees during the day without this posing a problem. While in Brittany, these would be very unusual temperatures. When you can’t rest at night, the body becomes exhausted and it becomes dangerous for your health.
What temperatures are expected in these four departments?
We based ourselves on a range that goes from 34 to 37 degrees. These four departments will therefore potentially have the highest temperatures on Sunday, around 36 or 37 degrees. For the minimums, in a city like Lyon, we may not go below 22 degrees at night while in the surrounding area, we will go down to 20 degrees.
These are not necessarily exceptional phenomena since we are already approaching July 10. The period of July-August, in the heart of summer, is the most conducive to high temperatures. It has nothing to do with the early heat waves that we had in June and which were more extensive.
How long will this heat wave last?
I can’t tell you yet since these are forecasts and vigilance that are reviewed every day. The hottest temperatures are expected from Sunday and Monday between Provence and the Rhone Valley. It will then be necessary to monitor the following days how it evolves. It really is information that is reassessed every day.
How do you explain the difference between actual temperatures and perceived temperatures?
Even if it is a parameter that we do not necessarily take into account, we must first know that all bodies do not support heat in the same way. Then, depending on the wind, sunshine and humidity, we also have completely different feelings. If you’re by the sea with 32 degrees and a little wind, it’s not the same as being locked in a room with no air at all.