The average price of a gallon of gasoline in the United States rose 1 cent to an all-time high over the past three weeks, but absent a supply-affecting force majore, prices could fall dramatically in the coming weeks, according to the latest nationwide Lundberg survey.

The national average price for self-serve, regular unleaded gas was $3.0256 a gallon on August 11, an increase of 1.06 cents per gallon in the past three weeks, according to the survey of about 6,000 gas stations.

While the average price is an all-time high, adjusted for inflation gas would need to exceed $3.16 a gallon to match March 1981’s true all-time high, according to the survey.

Prices will likely begin to slide downward, especially with summer coming to a close, survey editor Trilby Lundberg said in an interview.

“Absent any extreme changes in oil or gasoline supply, retail prices are likely to slide,” Lundberg said. “Unbranded wholesale gasoline prices at terminals and refineries have been sliding, and these wholesale price cuts are on their way to the pump.”

“There’s plenty of gasoline, and gasoline supplies will be even more flush when we’re out of the summer driving season,” Lundberg said.

At $3.29 a gallon, Chicago had the highest average price for self-serve, regular unleaded gas, while the lowest price was $2.82 a gallon in Charleston, South Carolina, the survey said.

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