US heating oil prices remained around $4.25–$4.50 a gallon, more than 80% higher than a year ago, as supplies fell to their lowest seasonal level on record. US distillate inventories, which include diesel and heating oil, fell to 103.4 million barrels in the week ending August 21, the lowest level recorded for this time of year since comparable data began in the early 1980s. The situation is particularly concerning as demand typically rises in the autumn, driven by winter heating, Northern Hemisphere harvests and Southern Hemisphere planting. The Iran war has disrupted refined-fuel flows through the Strait of Hormuz, while Russia’s suspension of diesel exports and ongoing Ukrainian attacks on refineries are further tightening global availability. US refiners are benefiting from exceptionally strong demand, with diesel refining margins reaching record levels and exports rising sharply. However, increased US shipments remain insufficient to offset the global supply shortfall.