Most parts of the state the climate is Mediterranean , with rainy winters and dry summers . Reduces the influence of the ocean temperature variations , leading to a cool summer and warm winter. Because of the cold ocean currents along the California coast often is foggy . While moving inland the climate becomes more continental , with a large spread of temperatures in winter and summer . Westerly winds bring moisture from the ocean , and the northern part of the state gets more rain than the southern . The climate is also affected by the mountains that do not allow moist air from the ocean far inland.The northwestern part of California has a temperate climate , the total rainfall is 38-100 cm per year . In California Valley has a Mediterranean climate, but with a large spread of temperatures. For typical mountain climate of the mountains , snowy winters and moderately warm summers . To the east of the mountain ranges located desert areas with cold winters and hot summers.