California

limates of the wine regions in California are influenced by the cold water of the Pacific Ocean and the two mountain ranges; the Coastal Range, with an altitude of 1,200m along the Pacific coast line, and the Sierra Nevada Mountains 160 to 200km inland with an altitude of 3,000 to 4,000m. Generally, the climate is cooler closer to the Pacific Ocean with the cold California Current and is warmer and drier as it goes inland. As cool air meets warmer air from the land each morning, fog moves inland through gaps in the Coastal Ranges and valleys, up to 200km from the coast. The large temperature veriation between day and night means grapes mature slowly. There are various types of soil in California including volcanic, limestone, clay and sandstone with average rainfall of 400 to 600mm per year, concentrated in the winter. As it rains rarely in the grape growing season, drip irrigation and sprinklers are installed.

Napa Valley AVA is possibly the most famous region in America. It has a total surface area of 91,171ha of which around 45,000ha are planted with vines that produce 5% of California’s total wine. Napa Valley is a narrow strip of land, 50km from the San Pablo Bay in the south to the St.Helena Mountain in the north-west. Because of the unique topography, Napa Valley is only open to the sea in the south while sheltered by mountains in the east, west and north.

Sonoma is the historic wine region of California where vines were planted by the Franciscan Missionaries who came up from Mexico and by the Russian immigrants in early nineteenth century. Like in Napa Valley, there are many valleys and mountains in Sonoma which create the regions with diverse climates and widespread volcanic soils. 

Central Coast AVA is a large area stretching 400km north to south and 40km east to west along the Pacific Ocean with a total surface of 1,618,800ha. This AVA has approximately 360 wineries and produces about 15% of California’s total wine production. Wines of various types and quality are produced in this AVA from a range of climates influenced by the cool air and fogs from the Pacific.Central Valley AVA is a flat and fertile land between the Coastal Range and the Sierra Nevada Mountains. The northern part of the valley was formed by the Sacrament River while the southern part was formed by the San Joaquin River. The valley produces approximately 70% of California’s wine grapes along table grapes, grapes for juice and raisins. In the south, fertile soil and plenty of sunshine push up yields which allows for large wineries and vineyards that are fully automated. These wineries are known as factory wines as they produce a large quantity of cheap and fruity wines under big brand names.

Sierra Foothills AVA covers vineyards on the western slopes of the Sierra Nevada Mountains. The total vineyard acreage is 2,306ha producing only 0.5% of California wines. The major grape varieties are Zinfandel (930ha), Cabernet Sauvignon (242ha) and Syrah (226ha). Most of the vineyards are located at high altitudes with a cooler climate. Important smaller AVAs in this region known for premium Zinfandel include California Shenandoah Valley AVA and Fiddletown AVA in Amador County, El Dorado AVA and Fair Play AVA in El Dorado County and North Yuba AVA in Yuba County.

Southern California AVA includes the counties of Los Angeles, Riverside, San Bernardino and San Diego. The climate is very hot except for the small area of the Temecula Valley due to the Rainbow Gap which allows cool breezes to blow in from the ocean that get trapped in the valley by the coastal mountain range, creating a unique microclimate. Major grape varieties are Sauvignon Blanc and Chardonnay. Though this region has a longer tradition of growing grapes than northern California, it is still threatened by Pierce disease (a bacteria carried by insects) as well as housing developments into the vineyard areas from the large, ever growing cities of southern California.