San Gregorio is an unincorporated community in San Mateo County, California, with a population of 214 people. It is located in the San Francisco Bay Area, south of Half Moon Bay. Just east of Highway 1, it is one mile inland on Highway 84, from San Gregorio State Beach. It is also located 7 miles north of Pescadero via Stage Road and 8 miles west …San Gregorio is an unincorporated community in San Mateo County, California, with a population of 214 people. It is located in the San Francisco Bay Area, south of Half Moon Bay. Just east of Highway 1, it is one mile inland on Highway 84, from San Gregorio State Beach. It is also located 7 miles north of Pescadero via Stage Road and 8 miles west of La Honda via SR 84.