(CBS Local) — If you think it’s cold now, brace yourself. Weather researchers say that a polar vortex could hit the United States and Canada with extremely frigid temperatures either by the end of this month or in January.

Judah Cohen, a climate expert at Atmospheric and Environmental Research, said the latest studies indicate there is a chance Arctic air could push southward and blanket much of the Northern Hemisphere in late December or early January.

“Confidence is growing in a significant polar vortex disruption in the coming weeks,” Cohen tweeted on Dec. 10. “This could be the single most important determinant of the weather this winter across the Northern Hemisphere.’

It all depends on the polar vortex, a pool of freezing air 60,000 feet above the Earth’s Arctic surface, according to The Washington Post. If the vortex stays stable, the winter will be normal. But if it’s disrupted, it would bring especially frigid temperatures .

And while American climate experts say it could happen later this month, European experts are predicting that it will be felt in early January.

Bottom line: meteorology models used for predicting when a vortex aren’t always that reliable.

“Not all other models on board yet so still reason to be cautious,” Amy Butler, a scientist at the National Oceanic and Atmospheric Administration, tweeted.