The price of diesel fuel made national news last week when AAA reported it hit a new record high.

Official weekly numbers from the Department of Energy were delayed due to the holiday, but on September 9, the DOE’s Energy Information Administration reported average U.S. retail diesel price of $5.97, surpassing the previous high of $5.81 in June 2022.

That’s up 3.7 cents over a week ago, $1.97 higher than a year ago, and $2.41 higher than two years ago.

That’s very close to AAA’s numbers, which show the average diesel price reaching a record $5.94 as of September 9.

In California, EIA reports average diesel prices were nearing $8 a gallon at $7.76  –  55 cents higher than a week ago, $2.81 higher than a year ago, and $3.03 higher than it was two years ago.

AAA's numbers for September 9 showed the average price of diesel was 7.87 per gallon.

High Crude Oil Prices, Tight Refinery Capacity

Since the U.S. attacked Iran in February, oil prices have been high and remained high, as Iran’s control of the Strait of Hormuz has scrambled the logistics of transporting oil from the region.

It’s not just the Middle East conflict, according to the U.S. energy secretary. U.S. refineries are working at 98% capacity. If the Gulf Coast refineries are affected by a hurricane, that makes things worse.

Ukrainian drone attacks on Russian refineries are reducing diesel supplies from Russia, and Chinese refiners are also seeing falling outputs.

President Trump has been meeting with U.S. oil refiners to talk about increasing capacity, but with refineries running at near capacity, it’s hard to see how that could happen.

Diesel and gasoline prices are likely to remain high until shipping resumes in the Strait of Hormuz. Crude oil prices rose again last week with news out of Iran that it had targeted new strikes on U.S. forces in the Middle East. This week, they were driven higher by reported U.S. military strikes on Iranian tankers.

Crude oil prices are hovering between $90 and $100 per barrel.