There will be no escape from scorching temperatures on Monday, July 18, according to the forecasters.
On Sunday Météo France put 15 south-western Departements on red alert, while 51 others, including the neighbouring Alpes-Maritimes are on orange alert.
Even Brittany is likely to see a high of 39, whereas the previous high was 36.
A temperature of 40 degrees will be approached or surpassed in several parts of the country, Olivier Proust, a meteorologist at the state forecaster said.
The temperature in Monaco is likely to reach 33 or even 34 on Monday and Tuesday and continue in the low 30s for at least the rest of the week. The thermometer showed 31 at 22:00 on Sunday, and hot nights are set to continue.