There is a desert in California.
California . The Greater Los Angeles Area and the San Francisco Bay Area are the nation 's second - and fifth-most populous urban regions , respectively . California 's diverse geography ranges from the Pacific Coast in the west to the Sierra Nevada mountain range in the east ; and from the redwood -- Douglas fir forests in the northwest to the Mojave Desert in the southeast . Greater Los Angeles Area . However , this Census definition includes large , sparsely populated and primarily desert swaths of Los Angeles , San Bernardino and Riverside counties that are not part of the urbanized region . San Bernardino County , officially the County of San Bernardino , is a county located in the southern portion of the U.S. state of California .