San anselmo is located in Marin county California with a geographic area of 2.7 square miles. The total population in San anselmo is 12,623 with 48.6% male and 51.4% female. Children under age 5 represent 4.5% of the population, under age 18 equal 23.6% of the population and over age 65 is 17.0% of the population. The median household income is $146,179, per capita income is $87,047. There are a total of 5,224 housing units with 66.0% owner occupied. Education includes 6.0% of residents that are high school graduates and 75.1% with a bachelor's degree or higher. The average temperature in San anselmo in the summer is 76 degrees, and in the winter 43 degrees.