Martinez is a city and the county seat of Contra Costa County, California, United States. The downtown is notable for its large number of preserved old buildings. Martinez is located on the south side of the Carquinez Strait in the San Francisco Bay Area, directly facing the city of Benicia. Martinez has a Mediterranean climate . Summers are warm and dry, with some morning fog when the sea breezes are just right. Winters are wet and cool with occasional frost.
Although the common perception of Martinez is that of a refinery town, given the view from Highway 680 across the Shell refinery from the Martinez-Benicia Bridge, the city is in fact largely surrounded by water and regional open space preserves. The Martinez-Benicia Bridge carries Highway 680 across the eastern end of the Carquinez Strait to Solano County.
Primary employers include the Shell Oil Company, Kaiser Permanente, and the Veterans Health Administration.