Heavy rains fell near the rivers of Hem, Aa, Lien and Kanchi in the French province of Pas-de-Calais, putting 192,000 people at risk of flooding.
Due to flood risks, which began to fall on Monday, 74 schools in northern France will remain closed on Thursday and Friday.
The national meteorological service Meteo France said the continuous rains had also caused small rivers in northern France to flood their banks.
“Over the past 20 days, there has been three times as much rain as usual, and in some places, six days as much rain as normally falls in the whole of November.”
Aerial photographs taken by the newspaper La Voix du Nord showed large tracts of land sinking under water.