Merrimac is located in Sauk county Wisconsin with a geographic area of 0.8 square miles. The total population in Merrimac is 672 with 49.4% male and 50.6% female. Children under age 5 represent 9.5% of the population, under age 18 equal 24.6% of the population and over age 65 is 14.1% of the population. The median household income is $69,821, per capita income is $36,901. There are a total of 241 housing units with 80.1% owner occupied. Education includes 17.0% of residents that are high school graduates and 32.0% with a bachelor's degree or higher. The average temperature in Merrimac in the summer is 66 degrees, and in the winter 17 degrees.