A commercial grape-growing area since the late 1800s, this appellation is in Solano County, southeast of Napa Valley. As Green Valley is located just off San Pablo Bay, this region has a maritime climate characterized by cool, moist winds blowing inland from the ocean and bay. With its proximity to San Pablo Bay, fog is also a major climactic factor in the region. During the hot summer months, as heat rises off the vineyards, cool fog rolls in from the bay and cools the vines. These daily temperature fluctuations are essential to maintain good acidity in quality wines. The soils are described as very deep and well drained, on alluvial fans and stream terraces. The topography of the vineyard areas is relatively flat to slightly sloping, with the county itself being quite hilly. Green Valley is approximately one mile wide and four miles long and has about 800 acres under vine. The most prolific grape varieties are Gamay, Petite Sirah, Cabernet Sauvignon and Zinfandel.