Fuel costs across Montana climbed sharply on Thursday, with diesel prices reaching unprecedented levels in several communities while regular gasoline also posted significant gains.

Data from AAA indicates that the statewide average price for a gallon of regular gas rose to $4.54. This figure represents an increase of 3 cents from the previous day and marks a jump of 12 cents compared to prices recorded just one week prior.

Diesel Prices Surge in Key Markets

The most dramatic shifts occurred in the diesel market. The statewide average for diesel fuel climbed by 19 cents from Monday, settling at $6.14 per gallon. AAA reported that these figures have pushed Montana diesel prices to record highs.

In Great Falls, drivers faced some of the steepest costs in the state, with diesel priced at $6.23 per gallon. Missoula also saw a rapid escalation in fuel costs over a single day.

Diesel prices in Missoula jumped 17 cents between Monday and Tuesday. The price moved from $6.04 on Monday to $6.12 on Tuesday. This surge broke the previous local record for diesel, which stood at $5.97 per gallon.

Regional Gasoline Trends

While diesel drew attention for breaking records, gasoline prices also climbed in western Montana. In Missoula, the average price for regular gas reached $4.51 per gallon. This represents an 11-cent increase from the previous week.

The rapid day-to-day and week-to-week increases suggest a tightening supply or heightened demand affecting fuel distribution across the state. The data was compiled as of 7:34 AM on September 17, 2026.