The county is divided into two major geographical units by series of northwest/southeast running hills; the 32 mile long coastal plain and the Livermore-Amador Valley. Elevations in Alameda County begin at sea level and reach 3,700 feet in east county. Moderate year-round temperatures near the bay contrast with hot summers in the eastern area of the County.
The most heavily urbanized areas are the cities of Oakland and Berkeley, with a continuous pattern of suburban development extending southward to Fremont. The Livermore-Amador Valley, although still agriculturally productive, is experiencing considerable suburbanization.