National average diesel closed the week ending September 21, 2026 at $6.529 a gallon — a new all-time high, and the third straight week that record has been broken. The previous all-time high was $5.810, set back in June 2022. That record fell the week of September 7, fell again September 14, and has now fallen again this week, with the national average now running more than 12% above the old 2022 mark.
At the same time, a cluster of Midwest states is dealing with serious river flooding right as their fuel costs spiked hardest of any region on the board. If you're moving vehicle inventory through Illinois, Kansas, Missouri, Nebraska, Indiana, Kentucky, Michigan, Ohio, Iowa, Minnesota, Montana, North Dakota, South Dakota, or Wisconsin this week, both problems are hitting you at once.
Here's the full breakdown.
Diesel Prices by Region
What's driving it
No region posted a week-over-week decline. Not one. That's the headline underneath the headline: this isn't a single-region spike story, it's a broad, sustained run. The national average is up 16.6% over just the last three weeks — from $5.599 on August 31 to $6.529 on September 21.
The biggest single move is a three-way tie: Central Plains, Great Lakes, and Upper Midwest all rose an identical 6.88% week-over-week to an identical $6.68 a gallon. West Coast remains the most expensive diesel in the country at $7.519, running more than 15% above the national average. EIA's West Coast (PADD 5) series shows $7.456 for the same week — also its third straight week of setting a new all-time high, beating the prior record of $6.516 from June 2022. (West Coast actually broke that 2022 record twice this year: once in April, before falling back over the summer, and again starting the week of September 7.)
Weather Alert Summary
The seasonal turn
Extreme heat, which dominated our alert data through most of August, is completely absent this week. In its place: flood warnings across the Midwest and a run of coastal advisories up the East Coast — a clean seasonal handoff from summer heat risk to fall flood and coastal-storm risk.
Corridor Outlook
The three corridors carrying both this week's biggest fuel spike and its heaviest weather load — Central Plains, Great Lakes, and Upper Midwest — are the ones to watch most closely. West Coast carries the highest absolute fuel pressure on the board (a new all-time high for the third straight week) but almost no weather complication this week. South Central and Southeast are this week's calmest corridors on both fronts.
What We're Seeing on the Platform
Carrier market conditions currently favor carriers, and that's showing up in pricing behavior: a meaningful share of posted vehicles already have carrier offers clearing the posted price, and coverage on carrier matches remains strong across nearly all posted inventory. We're not seeing acute capacity scarcity concentrated in any single lane this week. That combination is exactly the environment where pricing to market matters most — the AHX Market Estimate Tool exists for weeks like this one.
What Dealers Should Do This Week
- Re-check pricing on any Central Plains, Great Lakes, or Upper Midwest vehicles today.
- Build in schedule buffer for the Midwest flood corridor.
- Treat the West Coast fuel level as durable, not temporary — this is the third straight week of a new all-time high, not a one-week blip.
- If you have sourcing flexibility, lean toward South Central or Southeast this week.
- Price to the AHX Market Estimate Tool before you post, not after a vehicle has already sat for a few days.
- Watch the Mid-Atlantic coastal advisories even though severity is low.
- Don't assume the Midwest cluster's identical pricing across three regions will hold next week.
FAQ
Is this the highest diesel has ever been, not just this year?
Yes, and it's not even the first week we've been able to say that. The previous national record was $5.810, set in June 2022. That record broke the week of September 7, broke again September 14, and has now broken again this week at $6.529 — three straight weeks of new all-time highs, now more than 12% above the old 2022 mark. West Coast is on the same streak: its previous record of $6.516 (also June 2022) has fallen for three consecutive weeks too, reaching $7.456 this week.
Why did Central Plains, Great Lakes, and Upper Midwest all move by the exact same amount?
All three jumped 6.88% week-over-week to an identical $6.68 a gallon — worth watching whether that holds next week.
Which region is most affected by weather this week?
Central Plains, with 14 of its 15 active alerts rated severe, almost entirely Flood Warnings.
Is any region getting relief this week?
No. Every one of AHX's ten tracked regions posted a week-over-week fuel increase.
What happened to the heat advisories from earlier this summer?
They're gone, fully replaced by flood and coastal-storm alerts — a clean seasonal transition.
Is there a seasonal demand factor adding to this?
Not right now. We're between Labor Day and Thanksgiving week, and none of our tracked seasonal drivers are active.
Where can I check current pricing before I post a shipment?
The AHX Market Estimate Tool gives you a real-time read before you post.
Sign up free at autohaulerexchange.com.
Data attribution: EIA weekly retail on-highway diesel survey, week ending 9/21/26, plus EIA historical series EMD_EPD2D_PTE_NUS_DPG (national) and EMD_EPD2D_PTE_R50_DPG (West Coast/PADD 5), fetched directly from eia.gov on 9/22/26. NWS/NOAA weather alert data as of 9/22/26. AHX platform data as of 9/22/26. No CDG newsletter or Autonews industry context was available for this week's pull.
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