Hail, heavy rain and winds measured as peaking at 224km/h swept across the French island on Thursday as parts of the country - which has been hit by a series of heatwaves and severe drought - saw more rain in just a few hours than in recent months combined.

A 13-year-old girl died when a tree fell on a campsite and a 72-year-old woman was killed when her car was struck by a beach hut roof, authorities said.

The third victim died when a tree fell on a bungalow, local newspaper Corse Matin reported.

French weather forecaster Meteo France said the island, a popular tourist destination, was hit by "violent thunderstorms with strong tornado-like gusts ... causing significant damage".

It subsequently lifted a major storm warning, indicating the worst had passed for the Mediterranean island.

At least twelve people were injured, including one critically, and rescue operations were under way offshore, authorities added.

On France's mainland, grid operator Enedis said about 1000 households were without power after a storm hit the southern Loire and Ain departments.

On Wednesday evening in Marseille, streets were flooded and streams of water ran down steps in the port city, videos shared on social media showed.

Further north, drought has left the river Loire, famous for castles along its banks, so shallow that even flat-bottomed tourist barges can barely navigate it.

Australian Associated Press