For the fourth time this autumn, heavy rainfall is affecting the south of France. The next spell of bad weather is now set to hit the area between Montpellier, Marseille, and Montélimar.

By Friday, widespread rainfall of between 100 and 200 mm is expected. There is a renewed risk of flooding and flash floods, particularly in areas where large amounts of rain fall in a short space of time.

The problem is that the ground is already saturated in many places. In the Hérault department, there have already been several instances this autumn of 250 to 350 mm of rain falling within a few days. Further downpours could therefore quickly lead to problems.

It is no coincidence that this region, of all places, is repeatedly affected. In autumn, low-pressure systems often bring moist air from the Mediterranean to the south of France. In the Cévennes mountains, this air is forced to rise, causing the rainfall to intensify.