$5.89 a gallon became Wisconsin’s new average diesel record on Sept. 11, topping the prior $5.87 high set May 13, according to AAA.
Crude prices stayed elevated after U.S. and Iranian missile attacks on oil operations near the Strait of Hormuz, while the national diesel average rose above $6 for the first time.
Regular gasoline in Wisconsin also jumped 23 cents in three days to $4.05 a gallon, defying the usual fall seasonal easing in pump prices.
A year ago, Wisconsin diesel averaged $3.49 and the U.S. average was $3.71, underscoring how sharply fuel costs have climbed.
The pressure could last if Iran-backed Houthis keep control of several Saudi Red Sea shipping ports seized on Sept. 10, threatening another key energy route.