Natural gas prices jumped about 2 percent Thursday after the government reported a bigger-than-expected drop in supplies, and forecasters said January could be the coldest month since 1985.

Natural gas, which is used to heat homes and generate electricity, is still at higher levels in the U.S. than the five-year average. But the Energy Information Administration said that supplies are falling as homeowners and businesses crank up the heat. This month promises to keep thermostats up in much of the country.

Forecasters with Accuweather.com said a blast of Arctic air will sweep across the country starting at the end of this week. From Jan. 10 to 20, Chicago and Denver could see temperatures below zero. New York may only see highs in the teens, and southern cities could stay below freezing.

The EIA said natural gas supplies fell by 135 billion cubic feet last week, putting the storage level 1.5 percent below last year's level and 6.5 percent above the five-year average. The decline was more than analysts expected, according to Platts, the energy information arm of McGraw-Hill Cos.

Prices shot up immediately following the government report. Natural gas for February delivery rose 10 cents, or over 2 percent, to $4.54 per 1,000 cubic feet by midday on the New York Mercantile Exchange.

Meanwhile, oil prices fell as the dollar gained against other major currencies. Oil, which is priced in dollars, tends to fall as the greenback rises and makes crude contracts more expensive for investors holding foreign currency.

The dollar rose as a Labor Department report on jobless claims pointed to moderate job growth, and retailers reported the strongest increase in holiday sales since 2006. PFGBest analyst Phil Flynn said that oil prices have been propped up in recent months by federal stimulus programs, but "if we continue to get data like this, we're not going to need any more" stimulus plans.

Benchmark crude for February delivery fell $1.92, or 2 percent, to $88.38 per barrel on the Nymex.

Retail gasoline prices continued to rise. The national average added less than a penny overnight to a new national average of $3.08 per gallon, according to AAA, Wright Express and Oil Price Information Service. A gallon of regular is 12 cents higher than it was a month ago and 39 cents more than it was last year.

In other Nymex trading for February contracts, heating oil fell 3 cents to $2.51 per gallon while gasoline futures dropped about a penny to $2.43 per gallon.

In London, Brent crude gave up $1.11 at $94.39 per barrel on the ICE Futures Exchange.