On Saturday, the statewide average cost of a gallon of diesel rose by more than 10 cents from the day before, according to AAA. The nationwide average stands at more than $6.
The spike in California is close to $3 more per gallon than what drivers were paying this time last year.
Meanwhile, the price of regular gas is also on the rise. In Los Angeles and Orange counties, the average price is about $6. In Riverside County, the average is just under $6.
Drivers have been struggling with the steady rise of those prices as the war with Iran continues to disrupt the world's flow of fuel.
"All they have money for is filling up. They have to get, like, cash advances and stuff for food. It's rough," said Alyssa Barnes, a store clerk at a Southern California gas station.
Higher diesel prices mean more expensive transportation for a long list of everyday goods. That's because diesel is used for many freight and delivery networks. And some businesses have already passed along steeper costs to consumers in the form of added fees on online orders and packages in the mail.
Shoppers may feel more and more sticker shock, particularly in the grocery aisle. Perishable foods, like meat and produce, face one of the most immediate strains of expensive diesel because they need to be hauled in and restocked frequently - or may be harvested using farm equipment powered by the fuel.
It can take time for those costs to trickle down. But the surge in diesel prices doesn't appear to be going away anytime soon.
The Associated Press contributed to this report.