Winter-Blend Gas Is Here. Why Hasn't It Made Gas Cheap?
The fall switch to winter gasoline shaves real cost off every gallon. This year, it is being swamped by crude oil near $90 a barrel and a record September at the pump.
The cheaper gasoline arrived on schedule. The cheap prices did not.
Since Sept. 15, retailers across most of the country have been allowed to sell winter-blend gasoline, the fall changeover that usually takes some air out of pump prices. Yet AAA's report on Thursday, Oct. 1, 2026, put the national average for regular at $4.4137 a gallon, against $3.1605 a year earlier. September's monthly average of $4.33 set a record for the month, 50 cents above the previous September high of $3.83 set in 2023, according to AAA.
Both things are true at once. Winter gas really is cheaper to make, and drivers are paying more than $1.25 a gallon above last year anyway. The gap between those two facts is the whole story of this fall's fuel bill.
What is winter-blend gas?
The difference between summer and winter gasoline comes down to one property: how easily the fuel evaporates, measured as Reid vapor pressure, or RVP. In hot weather, highly volatile gasoline boils off from tanks and fuel systems and feeds smog. The Environmental Protection Agency caps summer RVP to "reduce evaporative emissions of volatile organic compounds from gasoline that are a major contributer to ground-level ozone," as its rules page puts it.
The federal summer limit is 9.0 psi in most places, with a stricter 7.8 psi standard in areas including Denver, Reno, Portland and Salem in Oregon, Beaumont-Port Arthur in Texas, and Salt Lake City. Gasoline blended with 10% ethanol gets a 1.0 psi allowance under the Clean Air Act.
Winter flips the problem. Cold engines need fuel that vaporizes readily, so winter blends carry a higher RVP. AAA has explained the stakes plainly:
"If the RVP is too low on a frigid day, the vehicle will be hard to start and once started, will run rough."
AAA
When does winter blend gas start?
For gas stations, the EPA's summer volatility season runs from June 1 to Sept. 15. Refiners, pipelines and terminals have to be compliant earlier, from May 1. Sept. 15 is therefore the date retailers may begin selling winter-blend fuel, according to NACS, the trade group for convenience and fuel retailers, which is why the fall switch is so often pinned to that day.
The spring switch is the expensive one. NACS calls the May 1 terminal deadline, when systems must be purged of winter fuel, "one of the biggest factors in seasonal price increases."
Why is winter gas cheaper?
Three forces stack up in the fall, and they push in the same direction.
The first is chemistry. Producing summer-blend gasoline adds roughly 15 cents a gallon to manufacturing costs compared with winter blend, NACS estimates. The second is demand: the group says fuel demand runs 10% to 15% higher in August than in February, so the summer driving peak fades just as the cheaper blend arrives. The third is refinery maintenance, which clusters in spring. NACS says refineries undergo turnarounds roughly once every four years, which works out to about 25% of them doing maintenance each spring.
Put together, the seasonal swing is real. Since 2000, prices have risen an average of 50 cents from their February low to their mid-May high, NACS says, and the fall unwinds part of that.
So why are prices still this high?
Because 15 cents of blend savings is small change next to crude oil. West Texas Intermediate rose $1.04 to close at $90.42 a barrel in Wednesday's session, AAA reported, and the auto club said crude prices "have dipped back into the $90 per barrel range," with gas still at its highest for this time of year.
Oil has swung hard in 2026. In late June, crude fell to pre-war lows as the Strait of Hormuz reopened; three months on, it is back near $90. When the raw material moves that much, the seasonal discount gets swallowed. The year-over-year gap in the national average, about $1.25, is more than eight times the blend savings NACS estimates.
The latest federal data AAA cited don't point to a demand surge, either. Gasoline demand slipped from 8.84 million barrels a day to 8.68 million, and total domestic gasoline stocks fell from 206 million barrels to 204.4 million. Lower demand helps prices; tighter supply cuts the other way.
Does winter gas get worse mileage?
A little, and that eats into the savings. "Winter grades of gasoline can have slightly less energy per gallon than summer blends," according to the Energy Department's fueleconomy.gov. The blend is only one piece of the cold-weather penalty. The same guidance says a conventional gas car's city fuel economy is roughly 15% lower at 20°F than at 77°F, and on short trips of 3 to 4 miles it can drop as much as 24%, thanks to friction, longer warm-ups and heaters.
For a household budget, the practical math is uncomfortable. A cheaper gallon that carries you slightly fewer miles, in a season when engines run less efficiently anyway, is not much of a discount. The cents that drivers can actually control lie elsewhere: prices can differ by $1 between stations a block apart, a spread that dwarfs anything the fall blend change delivers.
The winter switch, in other words, has already done its job. Whatever happens to the pump price between now and Thanksgiving will be decided by a barrel of crude, not by a few points of vapor pressure.
