Three departments in Brittany were on alert for flooding on Thursday, after a heavy downpours hit the western region since New Year's Day.
But with more rain forecast and water levels continuing to rise France's meteorological service Meteo France took the step of issuing a "red" level warning for the Finistère department in the far west of Brittany.
With several towns across the area under water Meteo France took the step of issuing a rare red level warning, which signifies that "dangerous weather phenomenon of an exceptional intensity" are forecast.
Authorities are warning residents to have the "utmost vigilance" and not to put their lives in danger.
The warning has been issued because the river Laïta, which flows into the Atlantic, has broken its banks and continues to rise.
The town of Quimperlé in Finistère experienced particular severe flooding on Wednesday and Thursday, as the Laita overflowed on to the streets of the town. Around 90 houses and businesses have been submerged and firefighters have had to evacuate numerous residents.
Morlaix has also been badly hit by the floods.
(Image from Météo France, shows Finistère placed on "red alert")
The departments Morbihan and I'lle-et-Vilaine remained on orange alert for flooding until 4pm on Friday at the earliest, with water levels dangerous in several regional rivers, and a "high tidal coefficient" present in coastal areas.
Petite pensée pour les habitants de Quimperlé, qui prennent bien cher en ce moment même pic.twitter.com/vjTEJgMK7K— Maylis (@maylis_stella) January 2, 2014
A woman aged in her 50s was killed in Morbihan on Wednesday, when a tree uprooted by strong winds fell on the car in which she was a passenger, French TV TF1 reported.
THese two videos from BFMTV and Le Figaro show the extent of the flooding in Quimperlé.
The floods in Brittany come just a week after the north of France was battered by fierce storms over Christmas that saw thousands left without power.