[2] Sonoma County is one of California's largest producers of wine grapes, far outproducing the Napa Valley AVA.

By the time of the Bear Flag Revolt in Sonoma and the subsequent annexation of California by the United States in 1854, wine grapes were an established part of agriculture in the region.

The vineyards of General Mariano Vallejo, military Governor of Mexican California and based in Sonoma, were producing an annual income of $20,000 at that time.

Commissioned in 1861 by the California legislature to study viticulture in Europe, he returned with more than 100,000 cuttings of premium grape varieties.

After the Civil War and before Prohibition, wineries such as Bundschu, Foppiano, Korbel, Simi, Gundlach, Quitzow and Sebastiani were established that still exist.

But wine consumption in America began to grow, and by 1999 Sonoma County had over 49,000 acres (198 km2) of vineyards owned by more than 750 growers and 180 bonded wineries.

[6] During the 2019 Kincade Fire, some wineries and vineyards experienced a week of intense heat, smoke and evacuation-caused neglect of newly fermenting wine.

Viticulture has existed in the area since the 1850s but the wine industry has only fairly recently experienced success beginning in the 1960s with Simi Winery.

Significant purchases of vineyard land by E & J Gallo Winery in 1988 and Kendall-Jackson in 1996 also raised the profile of the Alexander Valley.

The AVA is surrounded to the south, east and west by the Sonoma Mountains and to the north by the city of Santa Rosa.

The 27,500-acre Fort Ross-Seaview AVA is located in the western part of Sonoma County and contains 18 commercial vineyards on 506 acres.

Located at the southwestern corner of the Russian River Valley AVA, its close proximity to the Pacific Ocean makes it one of the coolest appellations within Sonoma County.

[3] The Los Carneros AVA spans the last, low hills of the Mayacamas Mountains dividing both Napa and Sonoma Valleys just north of San Pablo Bay.

The area's close proximity to the Bay has made it an ideal location for Pinot noir and Chardonnay production with producers from international Champagne houses such as Moët et Chandon (Domaine Chandon California), Taittinger (Domaine Carneros), and Cava producers planting vineyards or sourcing grapes from the area.

The AVA was proposed by E & J Gallo to accommodate wines made from a blend of grapes from scattered vineyards in Sonoma County.

[3] The Petaluma Gap was approved in December 2017 and takes its name from the geographic feature which allows cool ocean air currents to flow into the valley.

These winds, combined with the influence of San Pablo Bay, make the region ideal for Pinot noir, Chardonnay and Syrah.

The very high elevation of the mountain affects fog cover, hours of daylight, daytime and nighttime temperatures, rainfall, and wind — virtually every climatic element influencing wine grape production.

The appellation was granted AVA status in 1983 and accounts for about one-sixth of the total planted vineyard acreage in Sonoma County.