Why high diesel prices are coming at a particularly bad time

Diesel prices hit $5.68 a gallon on Wednesday, Sep. 2.

That’s a five cent increase from Tuesday and the highest average since the Iran war began. It’s also only 13 cents from the highest recorded price ever.

It all comes down to unfortunate timing: tariffs and wars aside, diesel prices usually have a seasonal upswing in the fall.

Even for those who drive gas vehicles, diesel was still involved, according to Patrick De Haan, head of petroleum analysis at GasBuddy.

“The cars we're driving don't get to the car dealerships without a semi truck using diesel,” De Haan said.

Same for apples, carrots, and bread. A diesel tractor tills up the crops, a truck brings them to a processing center, “then a distribution center, and then the grocery store,” De Haan said.

Thomas Goldsby, professor of supply chain management at the University of Tennessee, said companies often pass down those high diesel prices to consumers.

“Ultimately, they're looking to make sure that they cover their cost and can maybe make a dime here and there,” Goldsby said.

Diesel prices likely haven’t topped out. Demand for harvesting crops surges in the fall. Cooler weather means heating homes.

“Home heating oil comes out of the same distillate fuel pool that diesel does,” said Allen Schaeffer, executive director at the nonprofit Engine Technology Forum.

Combine those seasonal demands with current global politics, and even higher diesel prices are coming down the pipeline.