France has four broad climatic zones: the humid seaboard zone west of the line Bayonne-Lille with cool summers; a semi-continental zone with cold winters and hot summers in Alsace-Lorraine, along the rhodanian corridor and in the mountainous massifs (Alps, Pyrenees, Massif Central); an intermediate zone with cold winters and hot summers in the North, the Paris region and the central region; and a Mediterranean zone with mild winters and quite hot summers in the south of France.
Climate in the Paris area is variable. There is a chance of a downpour in spring or a thunderstorm in summer. Temperature ranges between 20°C and 26°C from May through October. Springtime in Paris is mild and relatively dry, and the autumn is equally extended. July and August are the warmest months. Daily average maximum temperatures range from 6°C in January to 26°C in August. The wettest month on average is October (71 mm), when heavy Thunderstorms are possible. Brittany in the far west is the wettest French locale, especially between October and November. July is the driest month for the Bretons.
In the South, the Mediterranean coast has the driest climate with any noticeable rain coming in spring and autumn. Provence (in the southeast) occasionally plays reluctant host to le mistral, a strong, cold and dry wind that blows in over the winter for periods of only a few days up to a couple of weeks.The Mediterranean coastline and Corsica have plenty of sunshine during the summer months, and refreshing sea breezes. Average daily maximum temperatures reach a warm 27°C in August, and an average of 12 hours of sunshine per day. 25-30 dry days per month can be expected during the summer season. On the Atlantic Coast and in Bordeaux, the climate is generally mild with temperatures averaging 11°C in winter, up to 27°C in summer, and rainfall distributed throughout the year. With the days fresh and possibly damp in the spring and often sunny in the autumn, the climate is one of the most important factors behind Bordeaux's high quality wine it produces.
The weather in the French Alps varies from north to south. The northern Alps (the Savoy) are subject to oceanic influences resulting in abundant precipitation year round with low temperatures, and cold winters with sometimes heavy snowfall. Briancon, in the Alps, has a mean temperature of -2°C in January, and 17°C in July. During the warm season, local winds blow along this region's wide valleys and by midday, warm air rises from the valleys, causing clouds to form around most mountain summits. The heights can sometimes attract storms that are both violent and spectacular. The southern Alps (Provence and the Cote D'Azur) enjoy a typical Mediterranean climate, with lots of sunshine, dry weather, clear skies and no mist or fog. Autumn is the best time of year in this region. Occasionally, violent storms may occur, but they are always followed by sunny spells.