California drivers are still paying some of the highest gas prices in the country this week, with the statewide average rising to $6.39 a gallon, its highest point so far in 2026. AAA called September 2026 a record-setting month for U.S. gas prices. In San Francisco and Santa Rosa, drivers are shelling out $6.58 and $6.60 a gallon respectively, while Yuba City offers the closest thing to a bargain at $6.16.
The statewide average actually rose roughly two cents over the past week, climbing from $6.37 to $6.39 a gallon, according to the Sacramento Bee. That figure sits less than 5 cents below California's all-time record of about $6.44 a gallon set in June 2022, and it exceeds the national average of $4.37 a gallon by nearly $2. Diesel has fared even worse: California's average hit $8.44 a gallon in late September, surpassing a record of $8.42 set just two days earlier, the newspaper reported.
A Record September, Nationwide
AAA reported that September 2026 was the most expensive September on record for U.S. gas prices, eclipsing the previous September record of $3.83 a gallon set in 2023. September's record-setting average remained below the all-time national high of about $5.02 a gallon from June 2022. Even so, the outlet noted average gasoline prices fell in 48 states over the past week, with Georgia and Ohio posting the largest declines, and diesel prices dropped in 48 states as well. California gasoline prices, meanwhile, fell less than 3 cents over the weekend, barely moving the needle for local drivers.
Crude oil prices fell back into the $90-per-barrel range, per AAA, as shipments increased through the Strait of Hormuz. But regional refineries are not yet fully able to move refined products through the strait, a bottleneck that is keeping fuel markets tight. GasBuddy said global fuel-market conditions are keeping both gasoline and diesel prices elevated nationwide, and the firm's analyst Patrick De Haan said prices could continue dropping in many states while some markets see increases instead, with price-cycling regions potentially seeing an upward swing.
Newsom Fast-Tracks Winter Blend
Governor Gavin Newsom announced on September 28 that California would suspend its usual gasoline-blend schedule, allowing winter-blend fuel to be manufactured, imported, distributed and sold immediately instead of waiting for the traditional November 1 transition date. Summer-blend gasoline is typically used through October 31 to reduce evaporation and curb smog during warmer months, but gasoline prices typically fall in autumn anyway as demand declines and stations shift to cheaper winter-blend fuel. Newsom invoked Senate Bill 237, a 2025 law authored by state Sen. Bill Grayson that gives state agencies emergency authority to suspend summer-blend rules during severe price spikes, according to the Office of Governor Gavin Newsom.
Winter-grade gasoline uses a higher proportion of cheaper butane and costs refiners roughly 15 cents per gallon less to produce than summer-blend fuel, which requires pricier, lower-volatility compounds, according to The Cool Down. GasBuddy said the early transition could offer California drivers some relief, though the Sacramento Bee reported GasBuddy also warned that recent declines at the pump could prove temporary given how volatile global oil markets remain. Newsom blamed the high prices on rising global oil costs tied to the conflict in Iran, saying that the war has driven up oil prices worldwide.
Why California Prices Swing So Hard
Part of the reason California feels these shocks more acutely than other states comes down to geography. The state operates as what the California Fuels & Convenience Alliance calls a fuel island, with zero inbound interstate refined petroleum pipelines, leaving it dependent on ocean tankers that can take 10 to 34 days to arrive plus up to 15 more days for refining. That isolation means local refinery outages or disruptions overseas cannot be quickly offset by shipping in fuel from other states, unlike in much of the rest of the country.
As part of his September 28 directive, Newsom also ordered the California Energy Commission to work with state petroleum monitors to publish regular public spot-market price reports for gasoline and diesel, aiming to increase transparency in wholesale fuel markets. He additionally directed the commission to collect information on renewable diesel and consider reporting its prices separately.
Taxes and Branding Add to the Bill
Layered on top of global market forces are California's own tax and retail structures. The state's gasoline excise tax automatically rose by 3.8 cents on July 1, reaching 63.4 cents per gallon, the highest state gas tax in the nation, according to the California Department of Tax and Fee Administration. Diesel is also subject to state taxes.
Retail branding plays a role too. A June 2026 presentation by the state's Division of Petroleum Market Oversight found that branded gas stations were generally more expensive than unbranded stations. CalMatters reported that Chevron stations averaged 44 cents more per gallon than unbranded stations during the last week of May. That dominance by major oil brands over retail distribution adds another layer of cost beyond crude oil itself.
For now, drivers from Riverside to Santa Cruz are left watching prices that move in small increments rather than dramatic drops. AAA said gas prices remain the highest ever recorded for this time of year, and while the early winter-blend switch may shave a few cents off the pump price in the weeks ahead, the structural forces keeping California fuel expensive — its tax rates, its clean-fuel mandates, and its isolation from the national pipeline network — are not going away.
