The below-normal temperatures are making it hard to spend a lot of time outside.

The extreme cold also may be pushing up the price to stay warm inside.

Natural gas prices have soared, said Ben Brockwell of the Oil Price Information Service in Wall, New Jersey.

"There's a lot of natural gas supply, but the problem is structurally getting some of these barrels to the market. So it's all based upon the infrastructure issues of pipelines," Brockwell said Friday. "You can make it, but if you can¹t get it to the market, the price is going to go up."

The price of propane is the highest it's ever been, up to almost $5 a gallon from $2 just three weeks ago, as demand peaks, he said.

Consumers who did not lock in home heating-oil prices with their suppliers at the beginning of the season also face higher costs.

Prices should begin to move lower again when the temperatures rise, Brockwell said.