The mild autumn in the U.S. is almost at an end, as a polar vortex is expected to sweep across the country this week, bringing with it plunging temperatures and arctic air.
According to meteorologists, by the end of the week temperatures will be sitting between 15 and 20 degrees below average in most states, and they're likely to stay that way for about two weeks.
If you've been procrastinating on digging out your coats and scarves for the year, time is almost up. The Midwest and east coast will get to enjoy temperatures of up to 60 degrees until about Wednesday afternoon. At that point, the cold air will come in from the west, and sweep across the whole country.
Experts are saying that the Great Lakes region will have particularly frigid conditions, and some are predicting the cold will bring some lake-effect snow along with it.
The south may be hit harder, however, as meteorologists are projecting temperatures that they don't see too often below the nation's capitol. Some computer models show 20 degree nights as far south as Atlanta, Georgia.
Even the west coast won't be spared, as they're expecting rain and snow storms to last throughout the weekend.