Arnold is located in Jefferson county Missouri with a geographic area of 11.5 square miles. The total population in Arnold is 21,144 with 49.3% male and 50.7% female. Children under age 5 represent 6.7% of the population, under age 18 equal 22.9% of the population and over age 65 is 17.8% of the population. The median household income is $64,678, per capita income is $30,378. There are a total of 8,518 housing units with 74.3% owner occupied. Education includes 31.5% of residents that are high school graduates and 21.4% with a bachelor's degree or higher. The average temperature in Arnold in the summer is 77 degrees, and in the winter 32 degrees.
