Castro valley is located in Alameda county California with a geographic area of 16.8 square miles. The total population in Castro valley is 64,392 with 49.2% male and 50.8% female. Children under age 5 represent 5.2% of the population, under age 18 equal 21.3% of the population and over age 65 is 16.9% of the population. The median household income is $113,150, per capita income is $49,004. There are a total of 22,071 housing units with 70.4% owner occupied. Education includes 15.2% of residents that are high school graduates and 47.3% with a bachelor's degree or higher. The average temperature in Castro valley in the summer is 76 degrees, and in the winter 43 degrees.