On the San Francisco Peninsula in California, the city of San Mateo—Spanish for "Saint Matthew"—is located in San Mateo County. The city borders Burlingame to the north, Hillsborough to the west, San Francisco Bay and Foster City to the east, and Belmont to the south. It is located about 20 miles south of San Francisco. The total area of the city, as reported by the US Census Bureau, is 15.9 square miles, of which 12.1 square miles are on land and 3.8 square miles, or 23.63%, are covered by water.

Warm, dry summers and mild, wet winters are typical of San Mateo's Mediterranean climate. Although the city is shielded from the Pacific Ocean by the Santa Cruz Mountains' Montara Mountain block, openings in the mountains can occasionally bring in severe afternoon winds and fog. 57.8 °F (14.3 °C) was the average maximum temperature recorded in January, while 78.0 °F (25.6 °C) was the average highest temperature recorded in September. The average amount of precipitation falls between 18.77 inches (477 mm) and 29.77 inches (756 mm) in 1973, the wettest year, and 11.16 inches (283 mm), the driest during 1953. Comparatively speaking, San Mateo experiences similar yearly precipitation levels and typically milder summers and colder winters than San Francisco International Airport.

With Central Park at its center and a Japanese tea garden as well as community events, San Mateo is home to over fifteen parks. There is bocce ball and a skate plaza in Beresford Park and a water play structure at Ryder Park. King Jr., Martin Luther. There are swimming pools at Park and Joinville Park, while volleyball and beach volleyball may be found at Parkside Aquatic Park. The 670-acre regional county park, Coyote Point Park, is home to the scientific museum CuriOdyssey and is popular for sailing and windsurfing. Public art is also on display in the city, such as the colorful mosaic artwork from 1963 in front of the Bank of America location on S. A shown in El Camino Real. P. Giannini's heritage in finance.

Preschool through K–12 education is provided to San Mateo citizens by the San Mateo Foster City School District and San Mateo Union High School District. Three public high schools—San Mateo, Aragon, and Hillsdale—as well as private institutions like Saint Matthew's Episcopal Day School and the Carey School for PreK–8 comprise the city's educational landscape. There are also private high schools, such as the Nueva Upper School and the all-male Catholic Junípero Serra. Situated in the western foothills, the institution of San Mateo is a community institution with over 10,000 students and a picturesque 153-acre campus overlooking San Francisco Bay. Universities in the area include Stanford University, which is about 12 miles south, and Notre Dame de Namur University in Belmont.

San Mateo benefits from three main freeways, situated strategically between San Francisco and San Jose: U.S. State Route 92, which crosses the San Mateo-Hayward Bridge to go to Hayward, Route 101, and Interstate 280. The authorized 2011 Bicycle Master Plan created a network of bikeways that demonstrate the city's commitment to encouraging cycling. SamTrans provides local bus service throughout the county and city, and AC Transit provides transbay bus service to Alameda County via the San Mateo Bridge. Three San Mateo stations—Hillside, Hayward Park, and downtown San Mateo—provide access for commuters to the rail services operated by Caltrain, which runs between San Francisco and San Jose. There are plenty of regular train stations, as well as additional services following San Francisco Giants games, thus public transit is widely available in the city.