The Clear Lake AVA (American Viticultural Area), located just north of Sonoma and Napa counties and east of Mendocino, contains the largest expanse of fresh water in California. Clear Lake itself accounts for nearly half of the AVA's total area and helps to moderate temperatures, making this one of coolest wine regions in California. As a result, Clear Lake is ideally suited to growing Sauvignon Blanc, which does very well here. Cabernet Sauvignon is also widely planted. The main worry for local viticulturists is the threat of flooding from the lake in the rainy season.
Sub-regions to the east and south of the Clear Lake AVA have individual climates capable of producing some outstanding wines.