California Wine - Climate and Geography

Climate and Geography

California is very geologically diverse region and is equally varied in the range of climates and terroirs that can be found. Most of the state's wine regions are found between the Pacific coast and the Central Valley. The Pacific Ocean and large bays, like San Francisco Bay serve as tempering influences to the wine regions nearby providing cool winds and fog that balance the heat and sunshine. While drought can be a viticultural hazard, most areas of California receive sufficient amounts of rainfall with the annual rainfall of wine regions north of San Francisco between 24-45 inches (615–1150 mm) and the more southern regions receiving 13-20 inches. Winters are mild with little threat of frost damage though springtime frost can be a hazard. To curb the threat of frost, vineyard owners will often employ the use of wind machines, sprinklers and smudge pots to protect the vines.

While California's wine regions can be generally classified as having a Mediterranean climate, there are also regions with more continental climates. Proximity to the Pacific or bays as well as unobstructed access to the cool currents that come off them will dictate the relative coolness of the wine region. Areas surrounded by mountain barriers, like some parts of Sonoma and Napa counties will be warmer due to the lack of this cooling influence. The soil types and landforms of California vary greatly, having been influenced by the plate tectonics of the North American and Pacific Plates. In some areas the soils can be so diverse that vineyards will establish blocks of the same vine variety planted on different soils for purpose of identifying different blending components. This diversity is one of the reasons why California has so many different and distinct American Viticultural Areas.