France issued a "red alert" for four southern regions on Monday afternoon amid a spell of excessively hot weather, with temperatures expected to reach 41 degrees Celsius in the Rhône Valley.
The warning, most serious in France, allows local authorities to suspend sporting or cultural events and close public facilities if necessary, Reuters writes.
The regions targeted by the alert, which took effect at 16:00 p.m. local time, are Rhône, Drome, Ardeche and Haute-Loire, Meteo France said.
It was the sixth time the French meteorological service had issued a red alert, part of the government's program to protect the population during periods of extreme weather, and the first such case this year.
"We are ready for this type of meteorological event. We are only strengthening prevention," Health Minister Aurelien Rousseau told reporters.
"Our message to the population is maximum vigilance."
At this stage, French hospitals are not witnessing a massive increase in the number of people seeking emergency care for heat-related illnesses, he added.
Earlier on Monday, Meteo France issued an orange warning for half of the country's territory, saying temperatures would reach between 35 and 38 degrees in most of the affected departments. "Peaks" of 41 Celsius were expected in the southwest and in the Rhone Valley.
Temperatures are expected to rise to between 40 and 42 degrees Celsius in the southern departments of Ardeche, Drome, Vaucluse and Gard on Tuesday afternoon, Meteo France said.
Separately, French energy company EDF said it extended an outage at its 2-gigawatt Golfeh 1,3 nuclear reactor in southwestern France on Monday as river water used to cool the reactor exceeded its maximum temperature due to a heat wave.
Some technical problems at the reactor also played a role in delaying the restart until August. 25, said the EDF spokesperson. The reactor has been offline since March 27 and was supposed to restart on Sunday.
Cooling water temperature levels at the Bugey plant and another reactor along the Rhone River in the southeast also exceeded government guidelines.
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