About This Place
San Geronimo (formerly, Nicasio) is a census-designated place (CDP) located in the San Geronimo Valley in Marin County, California in the United States. San Geronimo is located 8 miles (13 km) southwest of downtown Novato, at an elevation of 292 feet (89 m). The population was 446 at the 2010 census.
San Geronimo is located at 38°00′48″N 122°39′50″W / 38.01333°N 122.66389°W / 38.01333; -122.66389.
According to the United States Census Bureau, the CDP has a total area of 1.5 square miles (3.9 km²), all of it land.