Drivers can expect gas prices to rise by up to 5 cents per gallon because of a state law requiring a more expensive gasoline additive.
The higher prices will accompany California´s move away from MTBE, an additive that is blamed for polluting drinking water.
Refineries will start using the corn-based additive ethanol instead to cut down on air pollution.
California´s ban on MTBE is set to take effect by the end of next year.
The ban was originally scheduled to start January 1st but state officials worried a shortage of the new fuel would lead to spiking gasoline prices.
The state energy commission says the jump in prices should be moderate because many refineries took advantage of rock-bottom ethanol prices when the law was passed and locked into long-term contracts with ethanol suppliers.