Gas prices in parts of the Great Lakes region could fall sharply after a sudden refinery-driven spike pushed pump prices above $4 in several states last week, according to GasBuddy petroleum analyst Patrick De Haan.

Great Lakes Refinery Issues Start Easing

The average price for a gallon of regular gasoline jumped past $4 in Indiana, Michigan, Ohio and Wisconsin last week after those states had mostly stayed below that mark since the Middle East conflict began. Illinois nearly reached $5 a gallon on Wednesday, as regional refinery problems compounded seasonal maintenance.

De Haan said nearby Kentucky, Minnesota, Iowa, Missouri, Nebraska and Kansas could also see increases, though likely not as severe.

Drivers May See Relief Within Weeks

In a Tuesday update, De Haan said the refinery problems were "clearing up," which could bring relief of 20 cents to 40 cents per gallon in Indiana, Illinois, Ohio, Minnesota and Wisconsin. Iowa, Kentucky and Minnesota could also see some easing. He cautioned drivers not to rush to fill up, saying it could take "another week or two" for lower prices to show up at pumps.

With refineries in the Great Lakes getting back up to speed, diesel prices could fall from their near-$6/gal by 25-65c/gal so long as no new issues surface. This would bring most of MI/IN/OH/IL back into the mid-$5s, WI could head toward the upper $4s, low-$5s.

— Patrick De Haan (@GasBuddyGuy) May 5, 2026

Diesel prices are also expected to cool. De Haan said Great Lakes diesel prices could fall 25 cents to 65 cents per gallon if no new refinery issues emerge, bringing much of Michigan, Indiana, Ohio and Illinois back into the mid-$5 range and Wisconsin toward the upper $4 to low $5 range.

GOOD NEWS for GREAT LAKES- refinery issues clearing up- if you're in MI/IN/OH/IL/WI don't be in a rush to fill- the way things are looking, average gas prices could fall 20-40c/gal with diesel falling 25-60c in the next two weeks (but this could change if Strait destabilizes)

— Patrick De Haan (@GasBuddyGuy) May 5, 2026

Hormuz Tensions Keep Crude Prices Elevated

President Donald Trump announced "Project Freedom" over the weekend to guide vessels through the Strait of Hormuz, while Secretary of State Marco Rubio said on Tuesday that the administration would seek a U.N. Security Council resolution demanding Iran stop attacks, mining and tolling in the strait.

Crude prices remain the main driver of pump costs. The Energy Information Administration says crude oil accounted for 51.4% of the average U.S. retail gasoline price in 2025.

At the time of writing, the West Texas Intermediate (WTI) crude was trading at $100.64 per barrel. On the other hand, Brent crude futures traded at $108.02 per barrel.

High diesel costs are also hammering fishermen. National Fisherman, an outlet that closely covers the U.S. commercial fishing industry, reported last week that marine diesel has topped $5 in many states, forcing operators to reconsider trips, while shrimpers have warned that fuel costs are keeping boats docked.

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