Maintenance at U.S. refineries should leave some markets short on gasoline supplies, with West Coast markets suffering most, the Energy Department said.

The Energy Information Administration, the statistical arm of the Energy Department, issued an update on the impact of planned maintenance at U.S. refineries. Beginning in February, most refineries undergo regular maintenance as they switch from producing a winter blend of gasoline to a summer blend that requires additional measures to prevent vaporization.

For West Coast markets, EIA said planned maintenance is "light," though a Feb. 18 fire at an Exxon Mobil refinery in Torrance, Calif., could have a "significant impact" on gasoline production in the region.

"It is too soon to assess what that impact might be," EIA said in a Thursday report. "Gasoline inventories are at the low end of the 5-year range, and are sufficient to supply 21 days of average demand, one day below average."

Motor club AAA reports the state average price for a gallon of regular unleaded gasoline in California at $3.23 for Friday, up 4.5 percent from Thursday and 32 percent higher than one month ago. The national average price has increased 17 percent since late January.

Midwest markets are witnessing modest spikes in gasoline prices in part because of problems at BP's refinery in Whiting, Ind. The Chicago Tribune quotes labor leaders as saying there have been operational issues at the plant, though a BP spokesman was quoted as saying the refinery "is operating safely."

The United Steelworkers union is protesting working conditions at national refineries, though most energy companies say staffing and operational levels are normal.

Of Midwest states potentially impacted by any issues at BP's refinery, Michigan had one of the sharpest spikes in gasoline prices, up 3.5 percent from Thursday.

EIA said it estimates a full-year average retail price for a gallon of regular unleaded at $2.33 for 2015, nearly $1 less than last year's average.