Frontenac is located in St. louis county Missouri with a geographic area of 2.9 square miles. The total population in Frontenac is 3,538 with 50.1% male and 49.9% female. Children under age 5 represent 0.2% of the population, under age 18 equal 25.0% of the population and over age 65 is 15.1% of the population. The median household income is $174,676, per capita income is $88,585. There are a total of 1,167 housing units with 95.6% owner occupied. Education includes 1.5% of residents that are high school graduates and 84.8% with a bachelor's degree or higher. The average temperature in Frontenac in the summer is 77 degrees, and in the winter 32 degrees.