Killingly is located in Windham county Connecticut with a geographic area of square miles. The total population in Killingly is 17,267 with 46.2% male and 53.8% female. Children under age 5 represent 5.6% of the population, under age 18 equal 21.4% of the population and over age 65 is 15.9% of the population. The median household income is $66,071, per capita income is $32,478. There are a total of 7,004 housing units with 65.0% owner occupied. Education includes 36.0% of residents that are high school graduates and 21.8% with a bachelor's degree or higher. The average temperature in Killingly in the summer is 68 degrees, and in the winter 27 degrees.