River levels were receding early on Monday in southeastern France after "historic" floods left two people dead and more than 150 were airlifted to safety.

A third man disappeared while out on his boat and 4,000 homes have been left without power after the deluge in the department of Var, they said.

Local official Laurent Cayrel said one of the victims, a 73-year-old man, died in his basement, while the other was swept away in his car.

"The situation is very worrying, and it's not going to get any better tonight," he said on Sunday night, adding that there had been "record rainfall".

In the town of Hyeres, mayor Jacques Politi spoke of "a historic flood".

"We are at the end of the crisis," Var prefecture official Emmanuel Dupuis said, warning however that the ground remained saturated and the slightest rain could cause further damage.

However, there may be some respite, with one local official claiming river levels were receding, while still advising caution as an orange alert was in place.

Var, which lies on the stretch of Mediterranean coast known as the Riviera popular with tourists, is known for its sunny climate.

Emergency helicopters were deployed throughout the night, with 500 fire officers and 200 police on duty.

By late Sunday, 155 people had been airlifted from the worst-hit areas and efforts to evacuate residents by boat were continuing.

One local resident told how from her home she saw a huge wave sweep her empty car away before she was evacuated by helicopter with her five-year-old daughter.

"It was really staggering," she said. "We had called the fire brigade who told us to move the furniture upstairs... We had very little time, the house flooded very quickly."

French Prime Minister Jean-Marc Ayrault will travel to the affected area early Monday, his office said.

Late Sunday, authorities issued a separate flood alert for the river Rhone, which runs through southeastern France.

In an interview in a local paper Monday Ayrault said that a natural catastrophe announcement would soon be issued, a move which would release state funds for flood relief.