Four-dollar-a-gallon gas will return to Sacramento-area pumps as soon as today.

The price of gasoline in the Sacramento area rose another 6.8 cents over the past week to an average of $3.95 a gallon, according to national gas price tracker GasBuddy.com.

On Tuesday, AAA put the average price of unleaded regular in the area at $3.98 a gallon. Statewide, AAA said Tuesday's average price of unleaded regular was $4.17.

By GasBuddy's measure, the current Sacramento-area average price of gas is 1.9 cents per gallon higher than it was a year ago and 48 cents higher than last month.

Nationally, GasBuddy said, the average price of gas increased 11.9 cents per gallon over the past week to $3.68 – up 42.2 cents from last month and 16.7 cents higher than a year ago.

Analysts are blaming a stew of factors for the national trend – high fuel demand in China, crude oil rising from December's $87 a barrel to near $100 now and a strengthening U.S. dollar – but they said the chief culprit in California is tepid production at regional refineries.

"There's no doubt that the effort of refineries converting from winter-blend gasoline to summer-blend gasoline is having an effect," said Gregg Laskoski, senior petroleum analyst for GasBuddy. "There's no great time to shut down refinery operations, but now is a time when consumer demand is (historically) low."

He said West Coast refineries were producing at a 79 percent capacity last week, up from about 75 percent the week before. Nationally, however, refineries were producing last week at about 83 percent capacity, on average.

Laskoski noted that other communities are getting hit harder than Sacramento: "Los Angeles has climbed to $4.28 per gallon with a 55-cent average price increase in the past month, and that rate was surpassed in Chicago ($4.09) and Detroit ($3.86), where motorists saw 63- and 64-cent respective increases over the same period. New York crossed the $4 threshold, too."

Ominously, Laskoski said prices are likely to keep climbing.

"We're still projecting that prices will peak in April in the range $3.80 to $3.95 nationally," he said. "We did projections on two (California) cities. … We projected San Francisco in the $4.25 to $4.60 range and Los Angeles in the $4.35 to $4.65 range.

A perfect storm of refinery disruptions sent the average statewide price of unleaded regular to an all-time high of $4.67 a gallon on Oct. 9.

The disruptions came on the heels of an Aug. 6 fire that shut down a portion of a key Chevron refinery in Richmond.

Last fall's soaring prices prompted Gov. Jerry Brown to call on the California Air Resources Board to issue an order allowing in-state refiners to begin blending cheaper, winter-grade fuel earlier than the scheduled date of Oct. 31. ARB did that, but the effects did not start showing up at gas pumps for about a week.

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