The tornado hit a campsite in the town of Saint-Just-d’Ardeche, pulling down trees and destroying caravans and tents on Sunday afternoon.
A 42-year-old Frenchman died when a tree fell on him as the tornado hit. Five others were left injured although their conditions are not believed to be life-threatening.
Captain François Degrange, from the local police told AFP that trees had been brought down over a three to four kilometer radius.
“I have never seen that in my career before,” he said.
In a separate incident a woman was also killed by a falling tree at a campsite at Saint-Paulet-de-Caisson in the neighbouring Gard department.
According to Midi-Libre newspaper a baby was also injured as the storms hit and had to be rushed to hospital.
Hundreds of campers in the region have had to be evacuated.
The storms, which brought the mini-heatwave to an abrupt end, were accompanied by gale force winds and hailstones the size of tennis balls in some regions.
Nine departments in eastern France remained on alert for storms on Sunday evening, while other areas of north eastern France were on alert for heavy rain and floods.