Gas prices continue to slide.

FOX's Lisa Lacerra reports: 

The average price of gas down four cents over the past two weeks to $2.25 a gallon:

(Lundberg) "One of the reasons that gasoline prices are somewhat weaker is because the refiners can provide lower costs winter grade gasoline. But, even more importantly, demands for gasoline falls this time of year."

Oil industry analyst Trilby Lundberg with the Lundberg Survey. The highest price in San Francisco at $2.78. Tulsa, Oklahoma with the lowest at $1.95.

Lisa Lacerra, FOX News.