Why Wisconsin gas prices spiked in the last week, and what to expect this autumn

GREEN BAY - Gasoline prices' weekslong slide came to an end in the last week as Wisconsin's average price spiked by more than a quarter.

Hurricane season and a refinery fire will have that sort of impact, though.

The statewide average price for a regular gallon of gasoline rose to $3.76 Monday up 35 cents from one week ago, according to AAA Wisconsin. The increase in Wisconsin was much larger than the 5-cent increase that pushed the national average to $3.73.

Appleton and Green Bay, two communities that recently enjoyed some of the lowest prices in the state, saw the steepest week-over-week price increases at 51 cents and 46 cents per gallon, respectively. 

AAA on Monday reported the following average prices for a gallon of regular gas: 

• Wisconsin: $3.76, up 35 cents
• Appleton: $3.76, up 51 cents
• Green Bay: $3.81, up 46 cents
• Madison: $3.78, up 45 cents
• Milwaukee: $3.75, up 27 cents
• Wausau: $3.80, up 43 cents

Wisconsinites saw prices increase mainly because of refinery maintenance and a fire that shut down a Toledo, Ohio refinery and killed two workers last week. Nick Jarmusz, AAA's Wisconsin spokesperson, said the Ohio shutdown, in particular, forced gas and oil suppliers to find alternate supplies and reduced available supply, two factors that push prices higher. USA TODAY reported the Toledo refinery can process 160,000 barrels of crude oil per day. 

The refinery issues sent prices higher in Great Lakes, West Coast and plains states even though oil prices have continued to drop, normally an indicator that prices should fall. Consumer demand for gasoline rose 1.2% in the last week and online price tracker GasBuddy on Monday reported "wild fluctuations" in regional gasoline prices due to refinery issues. 

Patrick DeHaan, GasBuddy's senior petroleum analyst, on Friday projected the production issues would push prices up 25-65 cents per gallon. 

Now, oil and gas markets have turned the attention to Hurricane Ian as it approaches Florida this week. Jarmusz said the Gulf Coast's hurricane season generally introduces volatility to oil and gasoline prices.  

"Hurricane Ian could cause problems, depending on the storm’s track, by disrupting oil production in the Gulf of Mexico and impacting large coastal refineries," Jarmusz said in a media release. 

Last vestiges of lower prices gone by Monday

The consumer-reported last vestiges of the state's lower gas prices disappeared with the weekend. 

GasBuddy, which collects consumer price reports, on Monday listed a handful of convenience stores in cities like Milwaukee, Green Bay, Wausau, Appleton and Oshkosh with prices between $3.25 and $3.40, well below the $3.70 to $4 reported at most convenience stores. 

But a check of three such stores in Green Bay on Monday afternoon revealed those below-average prices were no more. All three stores displayed retail prices between $3.90 and $4.10. 

Overall, prices expected to stay on a downward trajectory 

Consumers wondering if this is the time to fill up might want to think about it in the near future, though prices are expected to drop as autumn advances. 

Refineries will complete scheduled maintenance and repairs will be made to the Toledo refinery, eliminating the reasons Wisconsin prices increased so sharply.

GasBuddy's weekly update on Monday said some regions affected could see prices increase as much as 25 to 75 cents while refineries recover and resume production. Once they do, Wisconsin prices should level off and begin to drop, Jarmusz said, provided hurricane season doesn't disrupt production too much.  

"Because of hurricane season, this is a volatile period for prices where they jump depending on where (hurricanes) hit, how long the season lasts," Jarmusz said. "We should continue to see a downward trajectory overall with some ups and downs within that."

Contact Jeff Bollier at (920) 431-8387 or jbollier@gannett.com. Follow him on Twitter at @JeffBollier.