King County had one gas station selling diesel gas at the lowest price of $4.25 per gallon during the week ending Dec. 13 2025, according to customer reports submitted to GasBuddy.
Diesel gas prices averaged $5.04 per gallon in King County.
Among 481 gas stations in cities within King County, 155 offered diesel gas.
The statewide average price of diesel gas in Washington was $4.81 per gallon for the week ending Dec. 13 2025, a decrease from the previous week.
U.S. gas prices continue to decline after reaching their lowest level since 2021, according to GasBuddy. The group projects the national average could dip below $2.80 per gallon during the holiday period, driven by increased oil production and lower seasonal demand.
The U.S. Energy Information Administration expects global oil stockpiles to keep growing into 2026, a trend that could weigh on crude prices in the near term. Brent crude is projected to average about $55 per barrel in early 2026 and remain near that level for the rest of the year. The agency notes that production decisions by OPEC+ and continued inventory building in China could limit how far prices fall.
Gas price data reflects cash payments. Some stations may charge higher prices for credit card transactions due to processing fees, though such surcharges are prohibited in some states and territories.
Data is accurate as of press time, but gas prices have been known to fluctuate on a daily, and even hourly, basis.
Information in this article was obtained from GasBuddy. The source data can be found here.
