SAN FRANCISCO (October 5, 2012)--Californians woke up Friday to discover that gasoline prices jumped overnight by up to 20 cents a gallon in some areas, prompting some stations to close and others to charge more than $5 a gallon.

The AAA Daily Fuel Gauge report said the average price of gas across the state was nearly $4.49 a gallon, the highest in the nation.

In Southern California, the price jumped 20 cents a gallon to $4.53 in Ventura and 19 cents to nearly $4.54 in the Los Angeles-Long Beach area.

In San Francisco, a gallon of regular gas was nearly $4.60.

In many areas, prices have jumped 40 cents in a week.

Refinery problems have helped send wholesale prices soaring.