(CNN) — It’s not even close to the summer driving season — in fact, it’s not even springtime — but as surely as February gives way to March, gas prices have begun their annual ascent.

The average price for a gallon of regular is now $3.53 a gallon, according to AAA. That’s 17 cents higher than it was just a week ago, and 23 cents higher than last month.

Analysts say gas prices are going up for two basic reasons: oil prices are rising, and refineries are shutting down.