The average price is 6.8 cents less than one week ago but 3.8 cents more than one month ago and 30.6 cents higher than one year ago, according to figures from the AAA and Oil Price Information Service.
The falling prices follow an 11-day streak of increases totaling 14.6 cents.
The dropping pump prices follow a large decrease in wholesale gasoline prices, according to Jeffrey Spring of the Automobile Club of Southern California.
The decreases are expected to end on Monday when a 3.5-cent per gallon increase in the gasoline excise tax goes into effect. The California Board of Equalization is required to adjust the excise tax rate by March 1 each year to ensure revenue neutrality under a law that went into effect in 2010.
Gasoline sales tax revenues fund local government programs, while the state excise tax on gasoline funds highway and mass transit projects throughout California.