U.S. average gasoline prices fell nearly 5 cents a gallon to $3.38 over the last two weeks due to a combination of weak economic conditions and fewer daylight hours, an industry analyst said on Sunday.

The national average for self-serve, regular gas is down 8.64 cents over the past month, according to the Lundberg survey. Since the last Lundberg report on Nov. 4, the average was $3.38 a gallon, down 4.82 cents.

The survey is based on some 2,500 gas stations nationwide.

"U.S. gas demand has been damaged by bad economic conditions, and demand since Nov. 5 has been struck a bit further because of the loss of daylight saving time," said Trilby Lundberg, editor of the survey. "Consumers always expand driving with more daylight hours and better weather; consumption drops off with fewer daylight hours."

Two weeks ago, the United States changed to standard time from daylight savings time.

Trilby said that the current average is nearly 51 cents higher than one year ago on Nov. 19.

San Francisco, at $3.78 a gallon, had the highest average price for self-serve, regular gas in the two-week survey period, while drivers in Albuquerque, New Mexico, paid the least at $2.96 a gallon.