Interior Minister Gérald Darmanin said on Tuesday morning that more than 1,500 firefighters were deployed in more than 600 operations last night.
In particular, the water level in the rivers Aa and Liane, in the Pas-de-Calais department, has suddenly risen sharply after heavy rain on Monday evening.
Schools in dozens of cities will remain closed today/Tuesday. The prefecture in Arras called on affected residents not to travel by car and to stay on the upper floors of their homes.
The water is expected to rise until the evening, also in other streams such as the Hem and the Canche. The French weather service reported on Tuesday that the worst of the rainfall has now passed.