Imperial Beach is a beach city in San Diego County, California, United States, with a population of 26,137 as of the 2020 census. It is in the South Bay area of San Diego County, 14.1 miles (22.7 km) south of downtown San Diego and 5 miles (8 km) northwest of downtown Tijuana, Mexico. Imperial Beach is the southernmost city in California and the West Coast of the United States.