While drivers across the nation are enjoying paying just a touch over two bucks a gallon for gas, Californians are getting hammered — again — with a new surge for a fill-up.

The state average climbed to $2.78 a gallon on Christmas Eve, up 13 cents in the past week after steadily falling since Labor Day. That’s compared with $2.01 a gallon across the U.S.

Drivers in the Golden State are noticing, and wondering why.

“What’s the story with the 15-cent hike at Chevron?” asked Jack Harper, 76, of Concord, where 12 days ago the price for premium was $2.85 at the station at Treat and Clayton, followed by a jump to $2.89 a few days later and then up to $2.99 this week. “Tell me there’s a gas shortage.”

Yep.

“You can guess the reason why — refineries,” said Allison Mac of Gasbuddy.com in Los Angeles. “There have been some unplanned maintenance issues causing the increase in the past week. We could see prices in California rise a bit more before they fall.”

Prices nationwide are lower than anytime since 2004, but the prediction this fall that California’s average would slip under $2.50 a gallon by New Year’s Day is a small lump of coal this holiday season.

California’s refinery casualty list runs up and down the state.

ExxonMobil’s Torrance plant hasn’t recovered from an explosion in February.

Tesoro’s Carson refinery is plagued by equipment problems — a catalytic cracker used to convert petroleum crude oil into gas broke down Nov. 23, and repairs my take until mid-January.