(CNN) -- Gas prices have jumped nearly 8 cents a gallon over the past two weeks, and are approaching the high for the year, according to a survey published Sunday.
The average price of regular is now $3.84 a gallon, just 13 cents below the peak that was reached this year in April, the Lundberg Survey found.
"It's due mostly, but not entirely, to storm-related refinery shutdowns," said publisher Trilby Lundberg.
Hurricane Isaac and the resulting power outages caused refineries to close, particularly in the Gulf region.
About a penny in the price jump is the result of a slight rise in crude oil prices, Lundberg said.
If crude oil prices remain stable, "then we will probably not see another rise in the next couple of weeks," Lundberg said.
Some U.S. refineries will be entering planned maintenance periods, but some refineries that shut down for the storm are re-opening, she said.
Also, U.S. demand generally drops in September.
The Lundberg Survey tabulates prices at thousands of gas stations nationwide. The latest survey was taken Friday.
The city with the highest average price in the latest survey was Chicago, at $4.30.
The lowest was in El Paso, at $3.44.
Here are average prices in some other cities:
Long Island: $4.03
San Francisco: $4.19
CNN's Josh Levs contributed to this report.