American motorists have seen the national average for a gallon of regular gasoline rise above $3.50 a gallon on just three occasions, but it has never happened this early in the year. Analysts say it's likely a sign that pain at the pump will rise to some of the highest levels ever seen later this year.

In 2008, average gasoline prices had hit inflation-adjusted records nationally by the summer, but they didn't climb above $3.50 a gallon across the U.S. that year until April 21, according to the AAA Fuel Gauge Report. It happened again last year, but not until March 6.

But $3.50 a gallon gasoline is already here in 2012, weeks before refineries typically shut down for springtime maintenance, and weeks before the states switch from their less expensive winter blends of gasoline to more complicated and pricier summer blends.

"This definitely sets the stage, potentially, for much higher prices later this year," said Brian L. Milne, refined fuels editor for Telvent DTN, a commodity information services firm. "There's a chance that the U.S. average tops $4 a gallon by June, with some parts of the country approaching $5 a gallon."