Rapid City Gas Averages $4.20; Diesel Near $5 on August 1

Regular gasoline is averaging $4.195 per gallon in the Rapid City metro, while diesel is averaging $4.973, according to AAA’s price check for Saturday, August 1, 2026.

Both fuel categories eased slightly from the previous day and the previous week. The short-term change is modest, however, and both remain substantially more expensive than they were one month and one year ago.

Regular gasoline remains just under $4.20

AAA’s Rapid City metro average for regular gasoline is down 0.8 cents from Friday and down 1.4 cents from the previous Saturday. The current average is still 25.0 cents higher than one month ago and 97.8 cents higher than the same time last year.

At the metro average, a 15-gallon fill-up would cost about $62.93. The total at an individual station can vary by location, fuel grade, timing and other local pricing differences.

Diesel remains just below $5

Diesel is averaging $4.973 per gallon in the Rapid City metro. That is 0.3 cents lower than the previous day and 0.8 cents lower than a week earlier.

The longer-term increase is larger: diesel is up 40.7 cents from one month ago and $1.435 from one year ago. A 50-gallon fill-up at the metro average would cost about $248.65 before station-specific differences.

What higher fuel costs mean locally

The slight easing may provide limited relief for commuters and households, but the larger increase since last year continues to raise operating costs for fuel-dependent work. Contractors, delivery operators, farmers, restaurants, repair companies and other service businesses may feel the impact through vehicle, equipment and delivery expenses.

Weekend travelers may also notice the difference on longer drives across western South Dakota. Higher fuel costs can affect trip budgets and the cost of transporting goods and supplies, although the AAA averages do not show how any individual business or household is responding.

For broader context, the U.S. Energy Information Administration‘s July 27 data put the Rocky Mountain regional average at $4.083 for regular gasoline and $5.141 for on-highway diesel. Those figures are regional and updated weekly, so they do not replace AAA’s more current Rapid City metro averages. KOTA Radio reported July 27 that regular gasoline in the Rapid City area was averaging about $4.20 per gallon.

AAA’s figures are metro averages, not the price at every Rapid City station. Share the highest and lowest pump prices you are seeing locally, along with the fuel grade and neighborhood.

Sources

• AAA South Dakota Fuel Prices
• Kotaradio
• U.S. Energy Information Administration