Seven departments in north west France were placed on orange alert -- the second highest warning -- for storms and flooding on Monday at 6 am by national weather agency Meteo France.
The Côtes-d'Armor, Ille-et-Vilaine, Morbihan departments in Brittany were on alert for violent storms, as were Mayenne and Sarthe in the Pays-de-la-Loire and Orne in Normandy.
Later on Monday morning seven departments in central and eastern France were also placed on Orange alert for storms (see map below).
The new departments on alert are: Aube, Doubs, Eure-et-Loir, Haute-Marne, Haut-Rhin, Haute-Saône, Vosges and Territoire-de-Belfort.
Members of the public in the affected areas are advised to take shelter in storms and avoid using any electrical equipment.
Meanwhile the floods alert in the Finistère department in Brittany was lifted late on Monday morning.
Finistère was already badly hit by storms on Sunday, with the downtown area of Morlaix flooded after heavy rains (see below).
People in these areas should are advised to remain vigilant to the risk of dangerous weather.
The alerts are expected to remain in place until 6 am on Tuesday, with the thunderstorms due to strike just before the afternoon and last into the evening.
"The rain will intensify in central Brittany, with the storms hitting before midday," said Meteo France, adding that there will be intense rainfall in short bursts.
In addition to the intense rainfall, the most violent thunderstorms may then be accompanied by hail and sudden gusts of wind of up to 80km/h.
Weather on Monday 2 pm - 5 pm. Photo: AFP
The national weather agency added that the rainfall could reach 50 - 60mm which is the equivalent of a month's worth of rain.