Holtsville is located in Suffolk county New york with a geographic area of 7.1 square miles. The total population in Holtsville is 18,574 with 50.0% male and 50.0% female. Children under age 5 represent 5.0% of the population, under age 18 equal 21.0% of the population and over age 65 is 15.2% of the population. The median household income is $109,701, per capita income is $44,585. There are a total of 6,352 housing units with 82.8% owner occupied. Education includes 31.4% of residents that are high school graduates and 28.9% with a bachelor's degree or higher. The average temperature in Holtsville in the summer is 70 degrees, and in the winter 27 degrees.
