Walnut is located in Los angeles county California with a geographic area of 9.0 square miles. The total population in Walnut is 29,764 with 48.6% male and 51.4% female. Children under age 5 represent 4.1% of the population, under age 18 equal 18.4% of the population and over age 65 is 21.1% of the population. The median household income is $108,264, per capita income is $41,691. There are a total of 9,106 housing units with 83.3% owner occupied. Education includes 9.6% of residents that are high school graduates and 61.5% with a bachelor's degree or higher. The average temperature in Walnut in the summer is 76 degrees, and in the winter 43 degrees.