Castaic is located in Los angeles county California with a geographic area of 7.3 square miles. The total population in Castaic is 18,479 with 50.6% male and 49.4% female. Children under age 5 represent 6.7% of the population, under age 18 equal 26.7% of the population and over age 65 is 10.2% of the population. The median household income is $120,574, per capita income is $42,258. There are a total of 5,656 housing units with 84.6% owner occupied. Education includes 17.9% of residents that are high school graduates and 41.4% with a bachelor's degree or higher. The average temperature in Castaic in the summer is 76 degrees, and in the winter 43 degrees.