American Viticulture Areas (AVAs) are federally recognized and designated wine growing regions that are able to demonstrate distinctive growing conditions that are not present in neighboring regions. While AVA’s can be defined by county or state boundaries, they must demonstrate their ability to influence grapes produced in the designated area by differences in climate and soil.

AVA’s are often named after the region of the state, the county or even named after the town where the grapes are grown. Historically, in the United States, AVA’s were and are named after counties, as counties automatically default as legal appellations of origin for wine, without having to prove their unique qualities. However, as wine growers realized that county-designated AVA’s were were quite large and had multiple microclimates and soil types, the AVA’s were reorganized to more accurately express the origin of the grapes grown in those wine regions. As of 2016, in the United States, the Alcohol and Tobacco Tax and Trade Bureau, which regulates AVA’s in the United States, reported there were 239 established AVA’s, with more than half of those located in California. Here, we are going to take a look at these AVA’s and learn more about what distinguishes each region from the other.

California's American Viticultural Areas

California’s AVA’s can be found from the Northern border of California with Oregon all along the Pacific coast to south of Los Angeles. They can also be found inland, from the Pacific Coastal Areas through the Central Valley and to the Sierra Foothills in the Eastern part of the State. The North American and Pacific Plate tectonics have made the geography and the soil within California very diverse. The activity of the plates has created small and large soil diversity to the extent that even within the same vineyard, soil types can differ greatly. It is this great soil diversity that makes for so many different AVA’s in California.

A geologically diverse state, California offers a variety of climates and subsequent terroirs for winemakers. California has the highest number (139 as of 2016) of AVA’s in the United States, with the majority of them concentrated along the Coastal regions, while the fertile Central Valley and Sierra Foothills are less concentrated, they are home to many productive and unique wine regions . In general, the coastal regions have a Mediterranean Climate, which is characterized by fog and cool ocean breezes, while the North Coast regions are defined by cooler temperatures and intense fog, unlike the warmer Central Coast and the hotter Southern Coast regions that have less to no fog, with a progressively more temperate climate. The Central Valley features a Continental Dry Climate, and drought can often be an issue, the Central Valley receives 13-20 inches of rainfall per year. Climate within the Sierra Foothills is considerably cooler, the grapes grow at a higher elevation and the growing season is much shorter.

Californian North Coast AVAs

Covering over 3,000,000 acres North of San Francisco, the North Coast AVA, is characterized by cool fog and ocean breezes from the Pacific Ocean. Home to many famous wine growing regions, the AVA includes the California Counties of Solano, Sonoma, Napa, Mendocino, Marin and Lake Counties. While the area shares the dominant ocean weather, the North Coast contains approximately 48 sub-regions, including Yountville, The Russian River Valley and Stag’s Leap. The cool coastal air produces exceptional growing conditions for Cabernet Sauvignon, Cabernet Franc, Pinot Noir, Merlot, Chardonnay and Sauvignon Blanc.

The Central Coast of California

Heading south, down the coast from the San Francisco Bay to Santa Barbara, the Central Coast includes the California counties of Santa Clara, Santa Barbara, San Luis Obispo, Monterey and Contra Costa and has approximately 100,000 acres planted with wine grapes. The cool coastal air, combined with a more temperate climate, account for this region being planted with nearly 50% Chardonnay. Other wine grapes that grow well here are Cabernet Sauvignon, Sauvignon Blanc, Merlot and Pinot Noir.

The Sierra Foothills

The Sierra Foothills is the second largest AVA in California at 2,600,000 acres and includes Yuba, Tuolumne, Placer, Nevada, Mariposa, El Dorado, Calaveras and Amador Counties. Due to the exposure and elevation winegrowers terrace the vines on the slopes and can then plant vines on sunny or shady slopes. The varying elevations from just a few hundred feet to 3,000 feet above sea level allow for exceptional growth of Zinfandel, Sangiovese, Syrah, Vio and Barbera. Grapevines were first planted here during the Gold Rush of the mid 1800’s when the iron-rich well draining red volcanic soil was discovered to be exceptional for growing low-yielding vines that produced dynamic high-quality wines.

The Southern Coast of California

Characterized by the warm weather of southern California and the cooling winds of the Pacific Ocean, the Southern Coast includes San Diego, San Bernardino, Riverside, Orange and Los Angeles counties. At just over 220,000 acres, the Southern Coast is the 3rd largest AVA in the state, with many microclimates. It is a growing region that spans an elevation from sea level to over 1600ft above sea level; the region produces exceptional Pinot Gris, Riesling, Chardonnay, Cabernet Franc, Cabernet Sauvignon, Merlot, and Montepulciano.

California's Central Valley

California’s Central Valley covers one of the largest agricultural areas in the country, and while this region produces over ¾’s of grapes for wine, juice and food in the state, the Central Valley has no official AVA designation. Yet the region which stretches from the San Joaquin Valley in the South to the Sacramento Valley in the North covers over 7 million acres and accounts for over 11% of total land in the state. The warm days and cool nights create a climate similar to a Mediterranean Climate and combined with deep loamy and rocky soils produce exceptional Old Vine Zinfandel, Merlot, Chardonnay, Cabernet Sauvignon, and Sauvignon Blanc.