January's Cold Reality Sets in This Week

Brian Donegan
Published: January 1,2017
A weather pattern change is arriving to start the month of January, ushering in much colder temperatures for a large swath of the United States that will last for several days in many areas.
(MAPS: 10-day Forecast High/Low Temperatures)
A southward diversion of the polar jet stream will allow arctic air to flow southward out of Canada into the Lower 48 states starting early in the week, dropping temperatures 20-40 degrees colder than average in the northern Plains and northern Rockies.
The cold will then spread into parts of the South and East through late week, although temperatures will not be as far below average in those regions as we will see in the northern Plains.

European model forecast jet stream (white lines) and surface temperatures (color contours) for Thursday, Jan. 5, 2017, based on the 00 UTC, Dec. 28, 2016, model forecast.

Chilly Forecast Details

High temperatures Monday will be 15 to 30 degrees below average in the northern Rockies and 10 to 25 degrees below average in parts of the northern Plains and Pacific Northwest. This translates to highs mainly in the teens and single digits from Montana and northern Wyoming into North Dakota and western South Dakota.

Forecast Highs Compared to Average Monday

The arctic air will spread a little farther south and east each day this week.
By late week, the below-average temperatures should cover much of the Lower 48 states, with the exception of parts of Florida.
Highs in the 20s are possible as far south as the northern Texas panhandle, which is at least 15 degrees below average for the first week of January.
(MORE: When Is the Coldest Time of the Year?)

Forecast Highs Compared to Average Next Friday

The worst of the cold, however, appears likely to remain locked into the northern Plains and Rockies, with highs remaining up to 25 degrees below average through late week. Some places won't even reach zero degrees Tuesday through Thursday, especially across parts of Montana, North Dakota and northern Minnesota.
(FORECAST: Missoula, Montana | Fargo, North Dakota | International Falls, Minnesota)
Since high temperatures will be so cold, you can bet on low temperatures being even more frigid.

Forecast Lows

Morning lows could reach the teens and 20s below zero in the coldest locations of the northern Plains and Rockies this week. These readings are 20 to 40 degrees colder than average for this time of year.
Although the air mass will be bitter cold, no widespread record lows are forecast at this time.
Wind chills will reach dangerously cold levels, placing you at risk for frostbite or hypothermia if you are outdoors and not properly bundled up. Early morning wind chills may fall into the 30s or possibly even the 40s below zero in the northern Rockies and northern Plains midweek.
(MORE: What Does Wind Chill Really Mean?)

Rockies, Plains Forecast This Week

This cold reality check won't reach the East until the end of this week, and the air mass will likely modify by that point and not be quite as bitter as it will be over the rest of the country.
However, it will be a noticeable temperature change in the East compared to early week. High and low temperatures will be 10 to 25 degrees warmer than average into midweek and then colder conditions return.

Five Day Forecast

Many locations in the East will see temperatures 20 to 30 degrees colder late in the week compared to the mild temperatures early in the week.
For more details on what the rest of January may bring, check out our January outlook.

MORE: Coldest Places on Earth