US diesel prices hit a record high on Friday, rising to an average of $5.85 a gallon as the six-month war with Iran disrupts global fuel supplies and pushes up transportation and production costs.Diesel is widely used by freight, delivery, farming and industrial networks. Higher prices are therefore expected to raise the cost of transporting a wide range of goods, with some businesses already passing on the additional costs to consumers through delivery and online-order fees.The impact is being felt particularly in the grocery sector, including produce, meat and other perishable goods that need frequent transportation. Farmers also rely heavily on diesel-powered equipment, adding to production costs.Experts warned that the pressure could increase if diesel prices remain elevated, with clothing, cosmetics, furniture and other goods also transported by diesel-powered trucks, trains and ships.Why diesel prices are risingUS diesel prices are now about 55% higher than before the US-Israeli war against Iran began on February 28, when the national average was around $3.76 a gallon, according to AAA.The latest surge has been driven by higher crude oil prices and concerns over fuel supplies in the Middle East. Much of the region’s tanker traffic has been disrupted by the conflict and bottlenecks around the Strait of Hormuz.Brent crude, the international benchmark, was trading above $95 a barrel on Friday, compared with around $70 before the war. Higher crude prices generally feed into pump prices for diesel and gasoline.Diesel prices have remained above $5 a gallon since July 15. Patrick De Haan, head of petroleum analysis at GasBuddy, said on X that 2026 is on track to be the most expensive year for diesel in US history.Low inventories add to pressureIndustry experts warned that diesel prices could rise further as seasonal demand increases. Farmers in the Northern Hemisphere typically use more diesel during the autumn harvest, while demand also rises ahead of the winter heating season.“Farmers and truckers typically use more diesel in the autumn, which raises the stakes for the current crisis and increases the risk of sharper price increases,” David Russell, Global Head of Market Strategy at TradeStation said, Reuters reported.“We’re entering a key period for diesel consumption with the lowest inventories on record for early September,” he added.US diesel inventories remain historically low. Distillate stocks, which include diesel and heating oil, were at their lowest August level for this time of year since 1982, according to Energy Information Administration data released Wednesday.The situation is particularly severe on the US East Coast, where distillate inventories fell to a record-low 19.3 million barrels in the week ended August 28, according to EIA data dating back to 1990.Refiners increase outputUS refiners have increased operating rates to multi-year highs to take advantage of strong margins and raise diesel production. However, supplies remain constrained by refinery disruptions in other parts of the world, UBS analyst Giovanni Staunovo said.Russia has also restricted diesel exports through September 30 after Ukrainian drone attacks targeted Russian oil refineries.The tight supply has pushed the US diesel crack spread, a measure of refining profitability, to a record intraday high of $108.02 a barrel on Wednesday. It was last trading at $101.10 a barrel, down 4.3% from Tuesday.Higher fuel costs threaten wider price increasesHigher diesel prices could ripple through the broader economy because the fuel is essential to trucking, agriculture and industrial activity.“This boosts transportation and production costs that can ultimately raise food prices,” said Andy Lipow, president of Lipow Oil Associates.Gasoline prices are also rising, though at a slower pace. The average price of regular gasoline stood at $4.15 a gallon, up from $2.98 before the Iran war, but below the 2022 peak of nearly $5.02.The last major diesel price surge came in June 2022, when the national average reached nearly $5.82 a gallon following Russia’s invasion of Ukraine and the sanctions imposed on Moscow.Adjusted for inflation, however, diesel prices have been higher in the past. The 2022 record would be equivalent to about $6.56 a gallon in 2026, while a 2008 price of $4.74 would equal roughly $7.20 today.The latest fuel surge could also create political challenges for Republicans ahead of the November midterm elections, as voters continue to assess the Trump administration’s handling of the economy and the Iran war.
