By Gary Richards

Get ready for a wild — and happy — plunge in gas prices.

California prices continue to slide a couple of pennies every day and could fall under $2.50 a gallon by Christmas. That would be up to an 80-cent drop in the statewide average.

That’s a prediction Allison Mac of GasBuddy.com made this summer and nearly all signs support her.

“I stand by that,” Mac said. “By the end of this year, we can see the California average down to the mid-$2-a-gallon range. Looking at the various factors that (cause) prices to fluctuate, things are pointing in the downward direction.”

Labor Day prices are at their lowest level since 2004. The national average stood at $2.40 gallon while it was $3.27 in California on Sunday.

Six of 25 California cities surveyed by AAA are selling fuel for under $3, and several more are close. San Jose-area drivers are getting gas for $3.11, in the East Bay the average is $3.14 and in San Francisco $3.28. All are 60 to 70 cents lower than last month.

Southern California and Central Coast drivers are paying the most, with Los Angeles at $3.48 and San Luis Obispo at $3.57. But head north, and it’s a lot less.

Across America, it’s far more than a few bucks at stake. Drivers across the U.S. will spend $1.4 billion less on fuel this weekend compared to last year. Each trip to the pump saves motorists about $15-$25, according the national auto club.

Which means there’s no panic at the pump.

Bob Caray, of San Jose, passed a Rotten Robbie station in Campbell selling gas for $2.95 last week. Even though he had less than a quarter of a tank of gas in his aging 1998 Ford Escort, he elected to skip filling up.

“I figured it might be down to under $2.90 if I wait a few days and I might save a few dollars,” he said, “so I’ll wait.”

It was $2.89 on Sunday.

There are numerous reasons to expect lower prices. Crude oil is selling well under $50 a barrel, demand will ease as summer driving eases, the Iran nuclear deal will put more oil on the worldwide market and refineries report few production troubles.

What could stymie the downward surge?

“Something to keep in mind about California, though, is that our margin of error is very small,” Mac cautioned. “Any hiccup at the refinery level can cause prices to spike.”

And Americans are getting behind the wheel like never before. A Federal Highway Administration report showed that U.S. driving topped 1.54 trillion miles in the first half of 2015, which was an all-time high.

But, for now, no hiccups and far less pain at the pump.

“It is unbelievable,’ said AAA spokesman Avery Ash, “that drivers are ending their summer vacations with the lowest gas prices for this time of year in more than a decade.”

Contact Gary Richards at 408-920-5335.