Middleburg is located in Clay county Florida with a geographic area of 19.6 square miles. The total population in Middleburg is 12,544 with 54.8% male and 45.2% female. Children under age 5 represent 4.8% of the population, under age 18 equal 21.6% of the population and over age 65 is 14.5% of the population. The median household income is $59,672, per capita income is $25,921. There are a total of 4,700 housing units with 82.6% owner occupied. Education includes 36.2% of residents that are high school graduates and 18.3% with a bachelor's degree or higher. The average temperature in Middleburg in the summer is 80 degrees, and in the winter 56 degrees.