Oakville is a census-designated place (CDP) in the Napa Valley of Napa County, northern California.The population was 71 at the 2010 census. Oakville's ZIP Code is 94562, and it is located in area code 707. The local economy is based on Napa Valley wine production, and Oakville was formally declared a distinct appellation within the Napa Valley AVA in 1993. There are currently 24 wineries and over 5,000 acres (20 km2) of vineyard located within the boundary of the Oakville AVA, among them are the Robert Mondavi Winery, the Opus One Winery, and wineries of Heitz Wine Cellars and Screaming Eagle.