Up to 40 centimetres of snow fell overnight in France's central southern region, including Languedoc-Roussillon, Provence, the Rhône valley and Mid-Pyrénées.
Such snowfall is "exceptional", especially at the beginning of March, according to national weather bureau Météo France.
The forecaster expects the snow clouds to make their way east on Monday, concentrating over the Hérault department.
Snow fall will nonetheless continue throughout the day in the more westerly Aude and Pyrénées-Orientales departments.
Météo France warns that the icy conditions will increase the risk of accidents, and advises drivers to be extra careful on the road.
Some 250 motorists in the Gard department were trapped in their cars on Sunday night after snow blocked the roads. Local authorities towed the vehicles and took their drivers to emergency shelters.
Heavy lorries (over 7.5 tonnes) have been banned from using sections of the A7, A8, A9 and A54 motorways, according to the traffic authority CRICR.
Several areas have also cancelled school buses.
Rail services are disrupted in Gard and Hérault, with delays on high-speed TGV trains from Languedoc-Roussillon as well as local services from Nîmes.