St. charles is located in St. charles county Missouri with a geographic area of 24.8 square miles. The total population in St. charles is 70,650 with 47.9% male and 52.1% female. Children under age 5 represent 5.4% of the population, under age 18 equal 17.3% of the population and over age 65 is 17.1% of the population. The median household income is $71,232, per capita income is $40,851. There are a total of 29,051 housing units with 66.1% owner occupied. Education includes 20.4% of residents that are high school graduates and 42.7% with a bachelor's degree or higher. The average temperature in St. charles in the summer is 77 degrees, and in the winter 32 degrees.