San Bruno (Spanish for "St. Bruno") is a city in San Mateo County, California, United States, incorporated in 1914. The population was 43,908 at the 2020 United States Census. The city is between South San Francisco and Millbrae, adjacent to San Francisco International Airport and Golden Gate National Cemetery; it is approximately south of Downtown San Francisco.
The city is located between South San Francisco and Millbrae, adjacent to San Francisco International Airport to the east and Golden Gate National Cemetery to the northwest. It is approximately south of Downtown San Francisco.
According to the United States Census Bureau, the city has a total area of , all of it land. The city spreads from the mostly flat lowlands near San Francisco Bay into the foothills of the Santa Cruz Mountains, which rise to more than above sea level in Crestmoor and more than above sea level in Portola Highlands. San Bruno City Hall sits at an official elevation of 41 feet (12.5 m) above sea level.
Portions of Mills Park, Crestmoor, and Rollingwood are very hilly, featuring canyons and ravines. Creeks, many of them now in culverts, flow from springs in the hills toward San Francisco Bay. Just west of Skyline Boulevard and outside of city limits is San Andreas Lake, which got its name from the San Andreas Fault. The lake is one of several reservoirs used by the San Francisco Water Department, providing water to San Francisco and several communities in San Mateo County, including San Bruno west of I-280.
San Bruno has a mild Mediterranean climate characterized by mild to warm, dry summers and cool, wet winters. San Bruno has much milder temperatures than most of the state. Owing to its relatively mild temperatures, the city's climate closely resembles that of an oceanic climate. Since 1927, the National Weather Service (formerly the U.S. Weather Bureau) has maintained a weather station at the nearby San Francisco International Airport (formerly Mills Field). According to the official records, January is the coldest month with an average high of 55.