The dominant climate of much of France is oceanic, also called maritime temperate. It prevails especially along the west coasts of continents in the latitudes of westerly airflow. In France the absence of mountains except on the southern and eastern borders permits this climate, with minor exceptions, to prevail in most regions. The oceanic climate features a mild winter with no monthly temperature averaging below freezing, a relatively cool summer, and, as a result, an extremely small annual temperature range. For instance, Brest, on the coast of Brittany, has a January average of 45 F (7 C) and a July average of 63 F (17 C) a range of only 18 F (10 C).
The Mediterranean climate predominates along the southern coast of France, particularly in the shadow of the Alps. Taking its name from the Mediterranean Basin, which it dominates, this transitional climate is found on the western coasts of all continents between latitudes 30 and 40 , north and south. The warm Mediterranean Basin at these latitudes produces mild winters, with an average January temperature of 47 F (8 C) at Nice. This famous resort city has heavy winter rainfall, about 34 inches (86 centimeters), but almost no rain in summer.
Because of the blocking effect of the Alps, Pyrenees, and Massif Central, temperatures remain higher and sunshine more frequent in the Mediterranean region than in the northern part of France. In summer, however, the northward shift of wind brings this region under the influence of dry subtropical weather that heads in from North Africa. Although temperatures are often very warm, especially away from the coast, this belt has little or no rain during summer.
The continental climate prevails farther to the east, away from the sea, and especially with increasing elevation. There, temperatures become lower during winter and snow remains on the ground for several weeks, though the weather is often sunny. Winter storms and their moisture can move easily across France, and so snow often tends to be heavy in the Jura and Alps, but temperatures are rarely excessively cold except on the highest peaks.