COSTA MESA (CBSLA) — The price for a gallon of regular gas has climbed as high as $4.05 in Orange County recently, which is why many drivers headed to Sam’s Club in Fountain Valley, where gas was going for $3.30 per gallon Monday — a full 75 cents cheaper than the most expensive stations.

“Gas keeps going up,” Mandy Hall, a driver, said. “I don’t know how they can justify doing like 10 to 20 cents a day, every time I turn around.”

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According to the Auto Club of Southern California, gas prices in Los Angeles County have hit their highest rates since December 2019, with self-serve regular gasoline getting more expensive for most of February.

The average price Monday was $3.74 per gallon in L.A. County, following 20 consecutive days of price increases.

And in Orange County, the news was not much better with gasoline prices increasing for 21 straight days to $3.73 for a gallon of self-serve regular gas.

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“I think it’s outrageous,” Timothy Bortvit, a driver, said. “It shouldn’t fluctuate that much just because there’s a problem some place, I don’t think. It’s gouging.”

So what’s actually causing the price of gas to go up? Experts say the recent spike is due to gas stations switching to a more expensive product known as a summer blend.

“We are looking at double digit price increases this last week and a half or so, and it’s mainly because we have switched to the summer blend of gasoline in our gas stations,” Marie Montgomery, Auto Club spokesperson, said. “So they’re selling the more expensive blend of gasoline that is required by air quality requirements.”

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By law, summer blend gas must arrive in Southern California counties by April 1 to meet air quality standards, bringing with it increased prices. The Auto Club said drivers might have to wait until May for prices to start stabilizing.