National fleet diesel prices fell for a second straight week, but fleets operating on the U.S. West Coast are seeing a very different story unfold.

According to the latest Samsara Fuel Spend Index, average U.S. fleet diesel prices declined 2.9% during the week of April 20-26 to $5.15 per gallon. That follows a 6% pullback over the past two weeks from the cycle peak reached earlier this month.

But the national numbers mask major regional disruption, Samsara notes in the report. California fleet diesel prices jumped 27.3% in a single week to $6.56 per gallon, while Washington state climbed 22.8% to $6.33. Hawaii reached $7.36.

Samsara said California’s $1.41 week-over-week increase was the largest single-state jump recorded during the current fuel cycle. Retail diesel prices in San Francisco briefly exceeded $8 per gallon earlier this month.

The report points to several factors driving the surge:

• The continued closure of the Strait of Hormuz
• Refinery outages and idled capacity on the West Coast
• Tight distillate inventories
• California’s specialized fuel blend requirements

“Pacific-facing states are absorbing the closed-Strait, lost-refinery-capacity setup faster and harder than the rest of the country,” the report noted.

Meanwhile, many Midwest and southern states saw temporary relief. North Dakota, Nebraska, Wisconsin and Oklahoma all posted declines of more than 7% week over week.

Still, the broader cost picture remains elevated. National diesel prices remain 56.4% higher than at the end of December, while the spread between diesel and gasoline prices remains nearly three times normal levels.

The report cautioned fleets against assuming the recent national decline signals lasting relief, arguing many operators are likely still benefiting from earlier contracted supply pricing rather than improving market fundamentals.