The average gas price in iowa is $0.13 cents higher than a month ago. Triple A says drivers in the state are paying $2.30 for regular. The Sioux City area posts the least expensive gas statewide at $2.20 a gallon, followed by Davenport at $2.21. It costs Des Moines drivers a state-high $2.40 to fill-up. Average gas prices nationwide are down a penny a gallon from a week ago at $2.34.