National weather agency Météo France has put nine departments on orange alert for strong winds and flood risks.
Orange is the second highest warning level on the agency's system.
All the departments on alert are in the north western corner of France: Ille-et-Vilaine, Loire-Atlantique, Maine-et-Loire, Mayenne, Vendée, Côtes-d'Armor, Finistère, Manche, and Morbihan.
Météo France said that gale force winds would bring more “very strong waves” to the Brittany coastline, particularly from the south.
The storm, which hit on Thursday evening, has already caused wave peaks of up to 12 metres.
Residents have been warned of the risks of “marine submersion”, where large waves and declining water levels can lead to flooding in coastal areas.
“The marine submersion could cause severe and rapid flooding, and the waves could damage coastal infrastructure,” the agency said.
The agency urged people to keep away from the coastline and out of the water at all costs.
It added that Friday would see winds of up to 130 km/hr.
“The wind may disrupt human activities and significant damage is expected,” Météo France said, adding that people should keep off roofs and be vigilant about the risks of falling trees.