San marcos is located in San diego county California with a geographic area of 24.4 square miles. The total population in San marcos is 96,219 with 50.1% male and 49.9% female. Children under age 5 represent 7.2% of the population, under age 18 equal 26.5% of the population and over age 65 is 12.7% of the population. The median household income is $86,408, per capita income is $35,232. There are a total of 29,749 housing units with 62.6% owner occupied. Education includes 16.5% of residents that are high school graduates and 43.6% with a bachelor's degree or higher. The average temperature in San marcos in the summer is 74 degrees, and in the winter 43 degrees.