Due to the fact that the sea's temperature remains fairly constant at deep depths (13ºC/56ºF at depths ranging from 200M to 4,000m) it is possible to swim here all year round. It is said that Greta Garbo loved to bathe in the sea here in winter and I must admit that I have seen some hardy souls take a midday dip in the Baie des Anges in Nice. In fact, there are days in January and February when the sun is hot enough to endulge in a spot of sunbathing and, with crystal clear skies and shimmering waters, it would be hard to resist a quick dip.

However, most. people really start enjoying the sea again in May as the weather is then, just perfect. At the end of June, when the tourist seasons starts in earnest, parascending, jet-skis and banana boats are available to rent along the coast through to September. 

Here's a chart with the monthly temperature:

Source: Météo France, Centre Départemental de Météorologie des Alpes-Maritimes.