San Ardo, California  San Ardo (formerly, San Bernardo) is a census-designated place (CDP) in Monterey County, California, United States. San Ardo is located southeast of King City, at an elevation of 449 feet (137 m). The population was 517 at the 2010 census, up from 501 at the 2000 census. San Ardo is near the point where the broad Salinas Valley ends at its southern terminus and pinches out within the converging portions of the California Coast Ranges, including the Santa Lucia Mountains on the west and the Cholame Hills and the Diablo Range on the east. San Ardo is located at . According to the United States Census Bureau, the CDP has a total area of , all of it land. This region experiences warm (but not hot) and dry summers, with no average monthly temperatures above 71.6 °F. According to the Köppen Climate Classification system, San Ardo has a warm-summer Mediterranean climate, abbreviated "Csb" on climate maps. The owner of the San Bernardo land grant, M.J. Brandenstein, laid out the town when the railroad reached his land in 1887. The San Bernardo post office opened in 1886, and changed its name to San Ardo in 1887. The former name of San Bernardo was changed to avoid confusion with San Bernardino, California. The huge San Ardo Oil Field is about south of town. Much of the local economy is based on agriculture (including farming and ranching), and servicing the oil field. At the 2010 census San Ardo had a population of 517. The population density was 1,150.7 people per square mile (444.3/km²). The racial makeup of San Ardo was 252 (48.7%) White, 1 (0.2%) African American, 3 (0.6%) Native American, 5 (1.0%) Asian, 0 (0.0%) Pacific Islander, 245 (47.4%) from other races, and 11 (2.1%) from two or more races. Hispanic or Latino of any race were 363 people (70.2%). The whole population lived in households, no one lived in non-institutionalized group quarters and no one was institutionalized. There were 140 households, 76 (54.3%) had children under the age of 18 living in them, 82 (58.6%) were opposite-sex married couples living together, 16 (11.4%) had a female householder with no husband present, 13 (9.3%) had a male householder with no wife present.