Lake County wine is a appellation that designates wine made from grapes grown mostly in Lake County, California and located north of Napa County. Although each region within Lake County has unique viticultural attributes, all are influenced by Clear Lake, the largest inland body of water in California. County names in the United States automatically qualify as legal appellations of origin for wine produced from grapes grown in that county and do not require registration with the Alcohol and Tobacco Tax and Trade Bureau (TTB). TTB was created in January 2003, when the Bureau of Alcohol, Tobacco and Firearms, or ATF, was extensively reorganized under the provisions of the Homeland Security Act of 2002.^[8]

Lake County enjoys a reputation for bright, concentrated red wines made from Cabernet Sauvignon, Syrah and Zinfandel, and fresh, aromatic whites made from Sauvignon Blanc.^[6] Cabernet Sauvignon has the most acreage, with Merlot a distant second.^[2][7]

Benmore Valley AVA was named after Benjamin Moore, a local 19th century cattle rustler. The valley is a high depression in the mountains of southwestern Lake County, and is much cooler than surrounding areas. Most of the grapes produced there were sourced by Geyser Peak Winery. There are no wineries or planted vineyards located within the boundaries of the AVA as of February 2018.^[9]

Big Valley District AVA viticultural area is located south of the southern shore of Clear Lake and established on October 2, 2013. It covers approximately 11,000 acres (17 sq mi) with six bonded wineries, 43 vineyards, and roughly 1,800 acres (730 ha) cultivated at its official recognition. Big Valley was the first settlement in Lake County and has a long history of agricultural activity. Sauvignon Blanc is the most widely planted varietal in this area. The boundaries of this region include Clear Lake to the north, Mount Konocti and the Red Hills Lake County AVA to the east, Merritt Road and Bell Hill Road to the south, and Highland Springs Road to the west.^[4][10]

Half of the area contained within the boundaries of Clear Lake AVA is Clear Lake. The moderating influence of the lake on the surrounding area results in a climate with less diurnal variation in temperature than surrounding areas. Elevations range from 1,300 to 3,000 feet (400 to 910 m).^[2] Clear Lake AVA is one of the coolest climates in California, which has led to success with grape varietals like Sauvignon blanc.

Established in 1981, Guenoc Valley AVA was the first American Viticultural Area designation granted to an area with just a single winery. Guenoc Valley is a small inland valley comprising an alluvial fan of Arroyo Seco and Conejo Loam series soils isolated from surrounding areas by rocky ridges.^[11]

High Valley AVA is located in the eastern part of the county. The valley is situated on high elevations ranging from 1,600 to 3,000 feet (490 to 910 m) in elevation. Red volcanic soils can be found on the hillsides while alluvial fans and benches on the valley floor provide well-drained beds for the vines.

Kelsey Bench AVA was established on October 2, 2013. The Kelsey Bench area encompasses about 9,100 acres (14.2 sq mi) with 900 acres (360 ha) of cultivation, one bonded winery and 27 vineyards when it was officially recognized.^[4] The term "bench" was selected to reflect the topography of the area with higher elevations and hills. Rich soils cover a large portion of the Kelsey Bench with good drainage favorable to growing grapes. The boundaries of the Kelsey Bench AVA are the Big Valley District AVA to the north, the 1,600 feet (490 m) elevation line that runs east of Kelsey Creek to the east, Kelsey Creek Drive to the south, and Adobe Creek Drive to Highland Springs Road to the west.^[12]

Red Hills Lake County AVA lies along the southwestern shores of Clear Lake, separating Excelsior Valley to the east from Big Valley to the west. The hills lie at the foot of Mount Konocti, a volcano which last erupted 11,000 years ago, but which is still regarded as active.^[13] The terrain is rolling hills with elevations between 1,400 feet (430 m) and 3,000 feet (910 m) above sea level.

On June 3, 2022, the TTB established Upper Lake Valley AVA. The Upper Lake Valley represents the eighth AVA located in Lake County, California. The topography of the Upper Lake Valley AVA defines a series of valleys running north-northwesterly from the shores of Clear Lake. These valleys and the surrounding hillsides sit at elevations of 1,330 to 1,480 feet (405 to 451 m) and are slightly cooler than the surrounding areas.^[14]

On August 4, 2023, TTB established Long Valley-Lake County viticultural area. The area lies to the north and east of High Valley AVA. It covers approximately 7,605 acres (11.883 sq mi) with 3 bonded wineries and 5 commercial vineyards cultivating about 149 acres (60 ha). The topography of Long Valley consists of a long, narrow valley floor and the surrounding foothills. The median elevation on the valley floor is approximately 1,322 feet (403 m) above sea level, and the foothills rise an additional 200 to 500 feet (61–152 m) above the valley floor. During the growing season, winds blowing through the valley cool the vines from the heat of the day. Cool air drainage provides protection from damaging late spring frosts in vineyards in the foothills, while vineyards along the valley floor require overhead sprinklers for protection. To the west and southwest, the established High Valley AVA has higher elevations than Long Valley, with its valley floor rising to 1,800 feet (549 m) and the surrounding ridges rising as high as 3,000 feet (914 m). To the east and south of the Long Valley AVA are steep hillsides with elevations that rise to 2,000 feet (610 m).^[15]