As of September 24, gasoline prices in Montana have risen 0.4 cents in the past week, averaging $2.96 per gallon according to GasBuddy.com. Prices were 35.3 cents per gallon higher than the same day one year ago and are 2.2 cents per gallon higher than a month ago. The national average is unchanged and stands 28.8 cents per gallon higher than a year ago.