Spring is not too far away, and neither is $4-a-gallon gasoline in California.

Energy experts predict a 50-cent rise in prices over the next few weeks as supplies tighten -- an annual event as refineries scale back production for maintenance, California converts to the more expensive summer blend of gasoline, more drivers hit the road and oil-exporting countries boost crude prices to around $100 a barrel.

But it's the conversion to the summer fuel formula that is the biggest reason for rising prices.

"That always causes a spike in prices by mid-March," said Cynthia Harris of AAA. "That will be happening."

Georgia Ellis pumps gas into her Lexus Hybrid at the Rotten Robbie gas station in San Jose, Calif. on Monday, Sept. 9, 2013.
Georgia Ellis pumps gas into her Lexus Hybrid at the Rotten Robbie gas station in San Jose, Calif. on Monday, Sept. 9, 2013. (Gary Reyes/Staff)

The statewide average hit $3.65 a gallon Tuesday in California, and $3.31 nationwide. Los Angeles has the most expensive gas among major cities in California at $3.72 a gallon, followed by San Francisco at $3.71. The Bay Area average is $3.63.

The national average price of gas could reach an estimated $3.55 to $3.75 per gallon, according to AAA. California gas is usually 30 to 40 cents higher.

Even the high end of the prediction is far below the record $4.67 a gallon set in California on Oct. 9, 2012, following a fire at the Chevron refinery in Richmond and pipeline disruptions between Northern and Southern California.

Big price spikes this time of year are common. Last year the national average jumped 49 cents from Jan. 1 to Feb. 27, peaking at $3.79. In 2012 pump prices surged 66 cents from the same date to a peak of $3.94 on April 5. In 2011 prices soared 91 cents to a peak of $3.98 on May 5.

But the frigid weather in the East and reduced driving have kept prices stable for weeks across the U.S. And higher prices could ease by Memorial Day.

"I believe this year will not bring record high prices, but we will indeed see prices rising to over $4 a gallon for much of the summer," said Patrick DeHaan, senior petroleum analyst at GasBuddy.com. "Prices are already starting to move higher, and we may not see relief until May or June, when refineries are done with maintenance and the supply of summer gasoline reaches adequate levels."

But over the course of the year, prices may stay relatively low. The federal Energy Information Administration said Tuesday that crude oil will average $93.22 a barrel in 2014, 11 cents less than last month's outlook.

And U.S. output has surged as horizontal drilling and hydraulic fracturing, or fracking, unlocked supplies trapped in shale formations from Texas to North Dakota, according to Bloomberg News.

"There is a good chance that average gasoline prices this year will cost less than in 2013, but it is not going to be cheap," said Bob Darbelnet, president and CEO of AAA. "The expected springtime rise in gas prices likely will be temporary, but that will not make it any easier to pay $60 or more to fill up your car."

Contact Gary Richards at 408-920-5335.