Diesel prices tick higher nationwide; West leads gains while Rockies hold flat
U.S. on-highway diesel prices edged up in the latest week of September 8, 2025, with the national average rising 3.2 cents to $3.766 per gallon. Regional moves were mostly higher as well, led by the West Coast, while the Rockies were essentially unchanged. The week’s modest firming came as crude markets digested an OPEC+ output decision and fresh U.S. stock data ahead of fall refinery maintenance.
Price analysis: week-over-week changes
Nationally, diesel increased from $3.734 to $3.766 per gallon (+3.2 cents, about +0.9% week over week). Regionally, the pattern was broadly similar, with slightly stronger gains in coastal markets and a muted move inland. The West Coast remained the most expensive region and posted the largest weekly increase in cents-per-gallon terms, while the Gulf Coast stayed the cheapest despite a small uptick.
Regional comparison
- East Average: $3.772, up 2.2 cents from $3.750 (+0.6%).
- Midwest Average: $3.754, up 3.2 cents from $3.722 (+0.9%).
- Gulf Average: $3.404, up 3.7 cents from $3.367 (+1.1%).
- Rocky Mountain Average: $3.754, up 0.1 cent from $3.753 (flat, +0.0%).
- West Average: $4.533, up 4.9 cents from $4.484 (+1.1%).
Market drivers: what moved diesel this week
1) OPEC+ signaled a modest supply increase starting in October. On Sunday, September 7, the OPEC+ core group agreed to raise output by 137,000 b/d beginning in October, a smaller hike than prior months. Into the week of September 8, crude prices hovered in the mid‑$60s per barrel as markets weighed the incremental supply against still‑soft demand. For diesel, a restrained crude rally tends to limit upside at the pump, with typical lags.
2) U.S. distillate inventories rose ahead of fall maintenance. EIA data for the week ended August 29 (released September 4) showed a 1.7 million-barrel build in distillate stocks, while refiners began dialing back units for seasonal work. Higher inventories can temper diesel price pressure even as crude fluctuates, though localized tightness can emerge as individual refineries go offline.
3) Demand signals were mixed. The ISM Services PMI for August, released September 4, rose to 52.0 (expansion), while manufacturing indicators remained soft in early September. For trucking fuels, a resilient services economy (freight for retail, leisure, and logistics) can support diesel demand, but ongoing factory weakness limits upside.
What it means for fleets
For the week of September 8, diesel’s uptick was modest and broadly consistent with a crude market that is stabilizing after months of declines. The West Coast premium widened again and remains a key budgeting issue for long-haul carriers; the Gulf Coast continues to offer the lowest rack and retail levels. With OPEC+ adding only small volumes in October and U.S. refiners heading into autumn maintenance, near-term pump prices are likely to trade in a narrow range, with occasional regional flare-ups tied to unit outages and logistics.
Outlook
Near term (1–3 weeks): Expect a mostly sideways price path with a slight upward bias if crude firms, but any further builds in distillate stocks could cap gains. Watch for refinery maintenance-driven tightness in specific markets and for spot diesel basis to widen around planned outages.
Operational tips for truckers:
- Shift more fueling to the Gulf Coast corridor where feasible to capture the widest regional discount.
- Use retail-minus-index or cost-plus contracts to mitigate rack volatility during refinery turnarounds.
- Monitor weekly EIA reports for distillate stock direction; sustained builds tend to ease retail pressure with a 1–2 week lag.
Bottom line: The national average moved higher but remains under $3.80. With OPEC+ proceeding cautiously and U.S. inventories no longer tightening, diesel looks set for range-bound trading into late September—though the West Coast premium and local maintenance schedules will continue to drive meaningful market-to-market differences.
This article was prepared exclusively for truckstopinsider.com.
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Source of diesel data is the U.S. Energy Information Administration (EIA).
