California
If 50 American states produce wine, Californian production alone represents approximately 85% of the country's production, making this state the 4th largest producer in the world behind Italy, France and Spain. The climate is strongly influenced by the Pacific Ocean which at this latitude is a cold ocean. The wine-growing regions located near the Pacific have an oceanic climate becoming Mediterranean the further inland you go from the ocean and it becomes more continental near the Sierra Nevada. Bays and openings to the sea, such as San Pablo Bay, act as thermal regulators on viticulture, particularly in Napa and Sonoma Valley.