San mateo is located in San mateo county California with a geographic area of 12.1 square miles. The total population in San mateo is 103,619 with 50.0% male and 50.0% female. Children under age 5 represent 6.7% of the population, under age 18 equal 20.6% of the population and over age 65 is 15.8% of the population. The median household income is $126,102, per capita income is $65,319. There are a total of 39,072 housing units with 52.7% owner occupied. Education includes 11.2% of residents that are high school graduates and 60.8% with a bachelor's degree or higher. The average temperature in San mateo in the summer is 65 degrees, and in the winter 43 degrees.