U.S. diesel prices have climbed to record levels, with the national average reaching $6.40 per gallon for the first time. The American Automobile Association reported a national diesel average of $6.3956 on September 17, 2026, marking the highest level on record.

The Energy Information Administration's weekly survey for the week ending September 14 showed the U.S. average at $6.285 per gallon, up 31.8 cents from the prior week and $2.546 higher than a year earlier. This surpassed the previous weekly high and pushed every major region above $6.00.

California led with an average of $8.039 per gallon. The West Coast overall stood at $7.250, while the Gulf Coast, the lowest-priced region, hit $6.027.

The surge comes as fuel markets face pressure from international developments, including conflicts involving Iran and ongoing issues in Ukraine. These factors have tightened global supplies of diesel and related products.

Trucking and agriculture sectors, which rely heavily on diesel, face higher operating costs that are likely to pass through to consumers in the form of elevated prices for goods. The rapid rise follows earlier increases this year, with prices more than doubling from early 2026 lows near $3.46.

The next EIA weekly update is scheduled for September 22. Daily tracking by AAA indicates the upward trend has continued into mid-September.