Our oil expert tells us he's surprised that the national average price for a gallon of gas has gone up more than 42 cents in the last month.

According to GasBuddy.com, today's national average is $3.68.  In Jacksonville, the average price for a gallon is six cents higher at $3.74.

"This is the time of the year when gasoline demand is relatively sultry, and that has a tendency to limit how much prices go up," GasBuddy's Patrick DeHaan says.

But AAA reports that gas prices have gone up steadily in the last 31 days.   It's a combination of factors - mainly from rising crude oil prices, production cuts and refinery closings.

The price of crude oil has jumped 10 percent in the last two months, according to the Energy Information Administration.  OPEC, the powerful cartel of petroleum exporting countries, is also believed to have cut production by about one million barrels of oil a day in the last few months, partly in response to rising oil production elsewhere such as the United States.

And on top of all that, many refineries have either shut down for maintenance or are preparing to ahead of their annual switch to summer blend gasoline, a different formula from winter blend.

DeHaan says there's a good chance consumers will have to pay even more to fill up their tanks this spring.

"Traditionally, gas prices rise anywhere from forty to sixty cents a gallon in late March through early May," he says.  "If that happens this year, it'll easily send the national average over four dollars a gallon."

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