Patrick DeHaan, an analyst for gasbuddy.com, said in a posting that "big increases" are expected for retail gasoline prices along the West Coast.
Chevron shut down a unit at its Richmond refinery in California following a fire this week.
"We are cooperating fully with regulatory officials to investigate the incident and do not know how long this unit will be down," Chevron said in a statement. The refinery makes transportation fuels and capacity is reduced by the shut down.
Motorist group AAA, in its daily fuel report, states that a gallon of regular unleaded gasoline Thursday in San Francisco, across the bay from the Richmond refinery, cost $4 compared with $3.85 last month.
The national average for a gallon of regular unleaded gasoline is $3.66, AAA reports.
The U.S. Energy Department's Energy Information Administration reports it increased its average retail price forecast for a gallon of regular unleaded to $3.49, up 10 cents compared with last month's prediction.
"EIA expects regular gasoline retail prices, which averaged $3.53 per gallon in 2011, to average $3.53 per gallon in 2012 and $3.33 per gallon in 2013," the agency stated.