As of September 10, gasoline prices in Montana have risen 0.7 cent in the past week, averaging $2.95 per gallon according to GasBuddy.com. Prices were 36.1 cents per gallon higher than the same day one year ago and are 2.3 cents per gallon lower than a month ago. The national average has dropped 2.4 cents per gallon during the last month.