The average for gas in the five-county Philadelphia area increased by 4 cents over the weekend to stand at $3.09 today, according to AAA Mid-Atlantic.

That marks a 19-cent increase in the last month, and a 37-cent increase from a year ago.

South Jersey's average went up 6 cents since Friday, to $2.91, which is 20 cents more than a month ago and 41 cents more than a year ago.

The national average was up 5 cents, to $2.95. That represents 12 cents more than a month ago, and 32 cents more than a year ago.

The auto club notes that this increase will hit shoppers right in the wallet, as the Christmas gift-buying season hits full stride. But AAA Mid-Atlantic cites Bureau of Transportation Statistics numbers showing that the median shopping trip is seven miles.

And that average trip would use up an average 0.34 gallons of fuel, costing $1.03, depending on the vehicle, according to the AAA Fuel Cost Calculator. (Of course, that doesn't even begin to cover the cost of buying all the items from the 12 days of Christmas; view those estimates here.)

Late last week, the price of crude oil hit its highest settlement since October 2008: $89.19 a barrel Friday.

With gas prices tending to follow the movement of oil prices, expect to pay more to fill your gas tank if crude oil prices continue going up.

Oil prices remained above $89 a barrel today after rallying to a 26-month high last week, fueled by hopes of increased demand amid a cold snap in Europe and rising speculative interest.

At the early afternoon mark in Europe, benchmark oil for January delivery was up 11 cents to $89.30 a barrel in electronic trading on the New York Mercantile Exchange. The contract added $1.19 to settle at $89.19 on Friday, the second time in less than a month that oil has reached the level where it was in the fall of 2008.

Prices were kept in check by a stronger dollar, which makes crude more expensive for investors holding other currencies.

There are widespread expectations that the price will hit $90 a barrel by year's end and head toward $100 a barrel by next spring, when traders begin looking ahead to the summer driving season.

"There is generally rather bullish sentiment in the oil market," said Victor Shum, an energy analyst at consultancy Purvin & Gertz in Singapore. "The $90 level is now becoming a magnet. The bulls in the market will try to push it across $90 but the question is, can it be sustained?"