There's good news for those planning to travel by car during the holiday season: Over the coming weeks, drivers are likely to see the lowest December fuel costs in years.

Gas prices have been steadily dipping since the summer and are now averaging solidly below $3 a gallon in the Philadelphia area. In recent weeks, it's been "remarkable" to see prices fall "so far, so fast," said Jim Lardear, a spokesman for AAA Mid-Atlantic.

In Pennsylvania, Philadelphia-area gas prices Thursday averaged $2.92 a gallon, down from $3.06 a month ago and $3.45 at this time last year.

Regional gas prices in New Jersey were averaging even lower, $2.63 per gallon, a drop from $2.75 last month and $3.26 a year ago.

With prices nationwide at a $2.73 average and likely to decline even further, motorists are in store for the cheapest December gas prices since 2009, AAA says.

The cheaper prices are giving a boost to U.S. auto sales and will likely help out consumers as holiday spending, travel, and events pick up.

"We see those signs every day when we drive," Lardear said. "I think that impacts what people think about their personal financial situation, whether they're feeling upbeat or down."

The travel group also expects the trend to continue: By New Year's Day, gas prices could fall 15 to 20 cents more a gallon, the travel group said in its monthly fuel report.

The decline is largely driven by a drop in crude oil prices. A strong supply of crude oil and OPEC's decision to keep up production mean low gas prices are likely through the winter, experts said. In addition, gas prices are typically lower in the winter because motorists drive less.

"There is little reason to expect gas prices to increase significantly until spring unless there is an unexpected spike in the cost of crude oil or an unanticipated disruption to domestic refining or distribution, which could send prices higher in an impacted region," AAA's recent fuel report said.

AAA data indicate that motorists are now more likely to encounter gas stations selling fuel for less than $2.50 a gallon, a price now found at 15 percent of stations, than stations with gasoline costing more than $3 a gallon. Gas is $3 or more a gallon at 12 percent of stations nationwide, AAA says.

In some places, gasoline costs well below even $2.50. On Wednesday, fuel prices at several Oklahoma City stations dropped to $1.99 a gallon or less.

In Philadelphia, the cheapest gas prices being reported Wednesday were $2.71 a gallon at the Eastcoast at Bustleton Avenue and Byberry Road and $2.72 at the Wawa at Krewstown Road and Grant Avenue, Eastcoast at Duncan Street and Aramingo Avenue, and Astro at Bustleton Avenue and Verree Road, according to the fuel-tracking website GasBuddy.