"If we knew, we would have been able to do a better job of forecasting," said Dale Mohler, senior meterologist with AccuWeather. "We thought in December the cold would take a break. But we didn't think it would take so long or flip this dramatically," he said.

The failure of forecasters like AccuWeather and others to predict the spring-like January came as some of nature's favorite weather oracles called it right - including the wooly bear caterpillar.

The slithery bug this year sported a fur coat with more brown than black, traditionally a sign of a mild winter to come, according to the Town and Country Almanac, published in Hagerstown, Maryland.

Mohler said the long warm spell came after the main jet stream, which steers cold air and storms throughout the Northern Hemisphere, swung farther north than usual, leaving the brutal cold in Canada this month.

"If you are on the south side of that, you are going to get a lot of mild weather from the Pacific Ocean or the Gulf of Mexico," he added.

Natural gas prices, which hit a record in mid-December, have been cut in half since then by the mild weather. But other fuels like heating oil remain lofty as geopolitical worries keep crude oil near $70 a barrel.

The government had been more cautious in this year's predictions. The National Oceanic and Atmospheric Weather Service's initial winter outlook forecast equal chances of warmer, cooler, or near-normal temperatures in the Midwest and East Coast from December through February.

One private forecaster who called it right so far for a warmer-than-normal winter was Todd Crawford, a meteorologist with WSI Corp. Crawford said every month WSI runs 12 weather models in house to forecast the weather, with the wooly bear caterpillar playing no part in the forecasts.