Coombsville received its designation as an AVA in 2011. Situated on 11,000 acres, Coombsville is a sub-appellation of the Napa Valley AVA. Coombsville ranges in elevation from near sea level at the Napa River on the west to 1,900 feet at the ridge of the Vaca Mountain Range. The Coombsville soils consist of rock, gravel and, some areas are layered with volcanic ash generated from the slow erosion of nearby Mount George. Proximity to San Pablo Bay contributes cooling effects of marine air and fog occurring almost daily during the growing season, maintaining a constant cool temperature to offset the warm daily sun. This allows for a longer growing season than other Napa Valley growing regions and allows the fruit the time on the vine required to develop a strong balance of tannin and acidity. Like most of Napa Valley, the region is dominated by the production of Cabernet Sauvignon, but also produces Chardonnay, Syrah, and Pinot Noir.