Scuba divers found two people dead inside an upended car lolling on a beach after torrential rains wrought havoc along France's Riviera coast in the night of Wednesday-to-Thursday, when flash floods also killed 10 on the Mediterranean island of Mallorca.
Meteorologists said major downpours were a classic phenomenon at this time of year but that exceptionally warm sea water along the Mediterranean coast of southern France probably reinforced the impact.
The year so far is France's hottest since 1900, according to the state meteorological service, Meteo France, and highs topped 25 degrees Celsius (77 Fahrenheit) on Thursday, well above normal for autumn in this part of the world.
The two people reported dead by the local government office in Saint-Maxime, near the famed film-festival city of Cannes, were found by emergency-service scuba divers, in a car found rocking on its roof in shallow-water waves.
The local prefect's office in the region told people there to avoid basement garages or any other underground spaces even if the worst of the downfalls, the equivalent of one month's rain in one day, appeared to have passed.
The stormy weather in the area and Mallorca coincided with a major hurricane that killed at least one in Florida.