Contra Costa County is located below Suisun Bay and east of the Oakland Hills. Settled in the late-19th century by Italian and Portuguese immigrants, it's home to some of the state's oldest surviving vines. These hearty Mediterranean varieties--such as Zinfandel, Carignane, and Mataro (aka Mourvedre)--have survived two phylloxera epidemics and continue to produce many rich, concentrated wines.
The soil in Contra Costa's vineyards can be extremely dry and sandy--so much so that people sometimes mistake it for beach sand. The microclimate here is characterized by large diurnal temperature fluctuations, thanks to cool maritime winds, which helps Contra Costa wine growers harvest at optimal maturity.