The national average price for diesel fuel leaped 7.4 cents to $2.234 per gallon for the week ending June 6, according to the U.S. Department of Energy.

The Gulf Coast region saw the biggest increase, with prices there rising a whopping 9.6 cents to $2.213 per gallon. The Midwest and the Lower Atlantic both had increases of 8.7 cents, with prices in those regions rising to $2.198 and $2.221 per gallon, respectively.

The East Coast as a whole posted an increase of 7.5 cents, rising to an average of $2.263 per gallon. New England came in at $2.353 per gallon, while the Central Atlantic region was $2.343 per gallon.

The Rocky Mountain region had a slight increase, coming in at $2.191 per gallon, while the West Coast jumped slightly to $2.339 per gallon. California rose more than 5 cents to $2.421 per gallon.

Crude oil prices fell at the end of the day on June 6, after spiking above $55 per barrel earlier on in the day.

According to The Associated Press, a strong demand for gasoline and diesel heading into the summer driving season has pushed U.S. oil refineries to their capacity. This, in turn, has sparked fears that heating oil supplies may be low by next winter.

Experts also blamed the increase in oil prices on a bleak forecast for this year’s hurricane season, which continues through the end of November.

Last year, Hurricane Ivan wrecked seven oil platforms and several pipelines when it tore through the Gulf of Mexico.