Westerville is located in Delaware county Ohio with a geographic area of 12.6 square miles. The total population in Westerville is 40,443 with 46.8% male and 53.2% female. Children under age 5 represent 6.6% of the population, under age 18 equal 22.1% of the population and over age 65 is 20.3% of the population. The median household income is $92,287, per capita income is $41,397. There are a total of 15,053 housing units with 77.7% owner occupied. Education includes 14.5% of residents that are high school graduates and 59.7% with a bachelor's degree or higher. The average temperature in Westerville in the summer is 73 degrees, and in the winter 32 degrees.