Irwin is located in Shelby county Iowa with a geographic area of 0.6 square miles. The total population in Irwin is 327 with 49.2% male and 50.8% female. Children under age 5 represent 4.6% of the population, under age 18 equal 20.5% of the population and over age 65 is 35.5% of the population. The median household income is $64,063, per capita income is $28,471. There are a total of 149 housing units with 82.6% owner occupied. Education includes 36.2% of residents that are high school graduates and 18.1% with a bachelor's degree or higher. The average temperature in Irwin in the summer is 72 degrees, and in the winter 23 degrees.