The national average for regular gasoline fell by a penny last week to $2.30 a gallon, but motorists on the West Coast saw pump prices rise while those in most other parts of the country experienced price declines.

Average prices for regular gas rose by 3 cents the past week in Alaska and California, 4 cents in Nevada, 5 cents in Washington and 8 cents in Oregon, the AAA Daily Fuel Gauge Report said Thursday (March 9).

AAA said in a statement that several refineries serving the West Coast “continue to run at reduced rates due to planned and unplanned maintenance,” which reduces the supply of gas and puts upward pressure on pump prices. Elsewhere, pump prices fell in most states, with the average for regular dropping 9 cents in Indiana to $2.21 a gallon. Prices fell by 7 cents in Michigan and 6 cents in Kentucky and Ohio.

The national average for premium gas was unchanged from a week ago at $2.82, according to AAA, and diesel was unchanged at $2.52.

Analysts predict that prices will rise through the spring months because refineries will shut down for seasonal maintenance and to switch to summer blends of gasoline that are cleaner burning but more expensive to produce. In addition, demand for gas typically picks up in the spring as motorists do more driving.