Soaring diesel prices ripple across the US economy as fuel costs nearly double since January

Filling up a semi-truck in January cost roughly $3.53 a gallon. By mid-August, that same gallon of diesel runs $5.454. That is a 54% price increase in less than eight months, and the reverberations are showing up in everything from grocery bills to construction bids. The national average retail diesel price, tracked by the US Energy Information Administration, has blown past the $5 per gallon mark repeatedly throughout 2026. August is on pace to become the most expensive August on record for diesel fuel, with prices averaging around $5.40 per gallon. For context, diesel cracked $5.38 as early as March and averaged $5.64 during some earlier stretches of the year. What is driving the spike The ongoing conflict in Iran sits at the center of the problem. Tensions in the Strait of Hormuz, a narrow waterway that carries an estimated 20% of global oil traffic, have created persistent uncertainty about supply flows. Layered on top of that are refinery assaults in both Russia and Saudi Arabia, which have knocked processing capacity offline at moments when the market could least afford it. Less refining capacity means less diesel output, even if crude oil itself were abundant. Stalled peace ...