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The average price for regular gasoline in Santa Rosa was $4.35 a gallon on Wednesday, up 10 cents from the day before and 20 cents from a week ago.

That’s also 50 cents higher than a year ago.

Prices were higher and the spikes even more dramatic at some North Bay stations. At a Chevron on Old Redwood Highway in Windsor, the price of gas on Thursday was $4.63 a gallon, a 24-cent increase from earlier in the week.

“We are in a roller coaster right now and prices will continue to rise,” said Cynthia Harris, a spokeswoman for AAA.

Kelly Warrender, a 51-year-old home care provider who lives in Rohnert Park, had visited a client in Windsor on Thursday. With her gas tank nearly empty, she waited until she hit Santa Rosa to fill up her tank, because she noticed prices there were lower.

“It’s really difficult, because I commute a lot,” Warrender said, adding that she would cut back on non-work trips. “I have noticed that it has gone up. It makes a huge difference.”

How much prices will rise is unclear. The highest recorded average for regular gasoline in California was $4.61 a gallon on June 19, 2008, according to AAA. For Santa Rosa, it was $4.55 that day.

The current spikes are being blamed on refinery problems that have limited gasoline supplies in California.

Harris said Exxon Mobile’s 150,000-barrel-a-day refinery in Torrance near Los Angeles lost power on Monday, and that a Chevron oil pipeline from Kern County to Bay Area refineries malfunctioned and had to be shut. She said refineries in Rodeo in the East Bay and in Arroyo Grande operated by Phillips 66 are closed for routine maintenance.

On top of that, repairs still are being made at a Chevron refinery in Richmond after an Aug. 6 fire caused damage to a crude distillation unit.

“It’s been a perfect storm,” Harris said.

The problems are limited to California. Elsewhere around the nation, gas prices have gone down as refineries switch to lower-cost winter blends, Harris said.

The average price for a gallon of gas in California was $4.31 on Wednesday, 53 cents more than the national average of $3.78, according to AAA.

At the Valero in Santa Rosa on College Avenue, a gallon of regular cost $4.49 Thursday evening, 25 cents higher than the posted price that morning, said Brian Avenell, 50, an engineer from Santa Rosa.

“What are you going to do?” Avenell asked. “You’ve got to drive. I can’t say I’m happy about it.”

There have been reports of some California stations running out of gasoline. But supplies should be sufficient in the near future to avoid widespread problems, said Alison Roberts, a spokeswoman for the California Energy Commission.

“You might not get it where you want, at the price you want, but you can find gasoline,” she said.

She predicted that the price surge will be a short-term problem and that prices will begin to go down once problems at the refineries are resolved.

This time last year, the average price for regular gasoline in Santa Rosa was $3.85 a gallon.

Staff Writer Cathy Bussewitz contributed to this report.

You can reach Staff Writer Derek Moore at 521-5336 or derek.moore@pressdemocrat.com. On Twitter @deadlinederek.