The slide in California’s gasoline prices could abruptly end Friday, with prices possibly jumping 30 cents a gallon due to seasonal changes in the state’s refinery operations, according to Consumer Watchdog.

The Los Angeles Times reported Thursday that the advocacy group said the switch to summer blend has triggered a jump of 52 cents a gallon on the gasoline wholesale market in Los Angeles this week, leading to the higher prices at the pump.

Although gas prices fell in recent weeks because supplies exceeded demand, prices typically climb in California this time of year when refineries switch from the winter blend of fuel to the more expensive summer blend required by the state.

Some of the sting from higher summer gas prices will be alleviated in July, when California drivers will pay 2.2 cents less for a gallon of gasoline, thanks to the Board of Equalization’s decision to cut the state excise tax.