Much of the U.S. Midwest and eastern coastal states were gripped by temperatures well below the freezing point last week because of a meteorological phenomenon called the polar vortex.
Michael Green, a spokesman for AAA, said the cold snap disrupted production at around a dozen refineries that make gasoline in the Midwest. This, in turn, caused regional shortages and price increases of nearly 10 cents per gallon in some markets.
AAA reported an average price Monday for a gallon of regular unleaded gasoline of $3.37 in Michigan, seven cents more expensive than the same time last week.
Green said the high number of refinery problems would normally create widespread problems but didn't.
"These very large price increases have not occurred in most areas because the polar vortex also weakened gasoline demand as fewer people drove their cars on the icy roads," he said in response to e-mailed questions. "This means that prices for most people have remained relatively stable with declining gasoline production balanced by a decrease in consumption."
Nationally, AAA reports a national average price of $3.31, a price that's remained relatively unchanged for the last 10 days.