A gallon of regular jumped to $4.38 Sunday in the Los Angeles-Long Beach area. That's up 4 cents from a day prior and 12-cents from last week.
In Orange County, gas went up to $4.35, up 5 cents from Saturday and 15 cents from last week.
Drivers in the Inland Empire are paying 4.32 a gallon, 3 cents more and 12-cents up from last week.
In Ventura, gas is going for $4.35 a gallon, a 2-cent hike from Saturday and a 15-cent hike from last week.
The increases are all because there only a few refineries produce the summer gas blend required in California. On top of that, four refineries are partially shut down.
"There have been some concerns about inventories, which have been going down," said Jeffrey Spring of the Automobile Club of Southern California. "That's where the biggest issue is. Inventories have at the lowest point as it has been since 2008, and that's what's driving the spot market up."