Mountain Center is a census-designated place in the San Jacinto Mountains, within western central Riverside County,California.
It lies along State Route 74 in the southern division of San Bernardino National Forest. Mountain Center lies just north of Lake Hemet, midway between Hemet and Palm Desert, and it is southeast of the city of Riverside, the county seat of Riverside County. Its elevation is 4,518 feet (1,377 m). Although Mountain Center is unincorporated, it has a post office, with the ZIP code of 92561.
According to the United States Census Bureau, the CDP covers an area of 1.9 square miles (4.9 km²), 99.91% of it land, and 0.09% of it water.