San marcos is located in Hays county Texas with a geographic area of 35.6 square miles. The total population in San marcos is 64,053 with 47.0% male and 53.0% female. Children under age 5 represent 4.1% of the population, under age 18 equal 13.1% of the population and over age 65 is 9.4% of the population. The median household income is $42,030, per capita income is $21,920. There are a total of 23,769 housing units with 29.1% owner occupied. Education includes 20.0% of residents that are high school graduates and 31.3% with a bachelor's degree or higher. The average temperature in San marcos in the summer is 83 degrees, and in the winter 49 degrees.