The cost of a gallon of diesel hit an all-time high in both Mobile and Baldwin counties on Tuesday, while regular unleaded continued climbing toward the records set here four years ago.
Mobile’s diesel average reached $5.99 on Sept. 15 — the highest figure ever recorded for the metro area, according to AAA’s fuel tracker. In the Daphne-Fairhope-Foley area, diesel also set a record at $5.94. Statewide, Alabama’s diesel average ticked just above $6.00.
Those are not gradual increases. They arrived over roughly a month.
How Fast the Climb Happened
Local diesel prices sat around $5.16 a gallon in mid-August. A week ago they were at $5.66. Tuesday’s record of $5.99 represents an increase of more than 80 cents in about four weeks.
The year-over-year comparison is more striking still. In September 2025, diesel in this market cost $3.41 a gallon. The current trend is on pace to double year-over-year costs.
Translated into an actual fill-up, the difference stops being abstract. Filling a 200-gallon tractor-trailer tank at last year’s price cost about $682. At Tuesday’s average, the same fill costs about $1,198 — a swing of more than $500 for a single tank.
For an owner-operator running multiple fills a week, that difference compounds into thousands of dollars a month against revenue that was contracted before the increase.
Why Diesel Moves Differently Than Gasoline
Diesel and gasoline are refined from the same barrel of crude, but their prices do not track each other precisely, and diesel tends to run more volatile.
Part of the reason is demand mix. Diesel, heating oil and jet fuel come from the same middle-distillate cut of the barrel, which means they compete for the same refinery output. Part of it is demand inelasticity: the trucks, trains, ships and farm equipment that consume diesel cannot meaningfully cut back when prices rise. A commuter can combine errands or carpool. A freight carrier with a delivery contract cannot decline to make the run.
That is why a diesel spike pushes into consumer prices across categories. Nearly every good sold in a store arrived on a truck, and fuel surcharges move through the supply chain toward the shelf.
What’s Driving It
According to AAA, volatility in the Strait of Hormuz has pushed crude oil back into the $100-per-barrel range — levels previously seen in July.
The Strait of Hormuz is the narrow waterway connecting the Persian Gulf to the Gulf of Oman and the open ocean, and it is the single most consequential chokepoint in the global oil trade. A substantial share of the world’s seaborne crude passes through it. Because there is no practical alternative route for most of that volume, disruption there — or even credible risk of disruption — moves prices worldwide regardless of where a given barrel is actually produced.
AAA noted the national average as of Sept. 10 was increasing despite seasonal demand that typically pushes prices downward this time of year. Pump prices are currently comparable to early June.
That detail matters for anyone hoping the increase corrects on its own. Prices are rising against the seasonal grain, not with it, which suggests the pressure is coming from the supply side rather than from an ordinary demand cycle that will ease as summer travel ends.
Regular Unleaded
Gasoline prices are up sharply as well, though they remain below their own records.
Regular unleaded averaged $3.89 in Mobile and $3.87 in the Daphne-Fairhope-Foley area on Tuesday. Both averages were down slightly from Monday but remained well above weekly, monthly and year-over-year figures.
This time last year, Mobile drivers were paying around $2.75 for a gallon of regular — more than a dollar less than today.
On a 15-gallon tank, that is the difference between $58.35 at Tuesday’s average and $41.25 a year ago, or roughly $17 more per fill. A household filling two vehicles weekly is absorbing something on the order of $130 a month it was not spending last September.
Still Short of the 2022 Peak
For all the movement, unleaded prices remain below the highs reached in the wake of Russia’s invasion of Ukraine.
Mobile’s all-time high for regular gasoline topped out at $4.62 on June 15, 2022. The Daphne-Fairhope-Foley area peaked three days earlier, on June 12, 2022, at $4.68.
Tuesday’s $3.89 leaves roughly 73 cents of headroom before Mobile matches that record.
Diesel is the exception to that comparison. It is not approaching a prior record — it has set a new one.
What It Means Locally
The gap between the two fuels is the story for a region built on freight. Mobile is a port city with a substantial trucking and logistics sector, and Baldwin County’s agricultural operations run on diesel equipment. Both counties also depend on the tourism traffic that drives down from inland states each season, and travel decisions are sensitive to the cost of getting here.
Households feel it in a narrower way but a constant one. Fuel is a nondiscretionary expense for anyone commuting to a fixed workplace, and an $17-per-fill increase lands on the same budget already absorbing higher grocery and utility costs.
AAA updates its regional averages daily.