The Coombsville AVA is an American Viticultural Area located within the Napa Valley AVA just east of the city of Napa. The appellation varies from near sea level at the Napa River on the west to 1,900 feet at the ridge of the Vaca Mountain Range. Proximity to San Pablo Bay contributes to the temperate climate of Coombsville. Cooling effects of marine air and fog occur almost daily during the growing season, arriving earlier and lingering longer than in the more northern regions of Napa Valley. Temperatures are less extreme during the winter frost season. The Coombsville soils are dominated by the volcanic rhyolitic tuff sedimentary rock and lava flows of the Vaca Range on the eastern side of the Napa Valley. Located in the wide alluvial deposits created by the wearing down of the hillsides