Gasoline prices climbed more than 3 cents in the past week, rising to the highest level since early May ahead of a storm that threatens to batter the U.S. oil refining belt, the federal government said on Monday.
The national price of gasoline rose 3.2 cents to $3.78 a gallon in the week ended Monday, the Energy Information Administration said in its weekly survey of service stations.
Gasoline prices have been climbing since mid-July as the cost of oil has spiked, up nearly 15 cents from a year ago.
Energy companies have begun evacuating offshore oil rigs and shutting down refineries as Tropical Storm Isaac heads toward the U.S. Gulf coast refining hub.
The storm is projected to strengthen into a Category 1 hurricane before making landfall in Louisiana by Wednesday.
Any significant damage to refineries or extended outages could force gasoline prices up further.
After Hurricane Katrina, a Category 3 storm, battered the Gulf coast in 2005, U.S. gasoline prices jumped more than 45 cents in a single week.
Similarly, gasoline prices rose nearly 20 cents in the aftermath of hurricanes Gustav and Ike in 2008.