Tuesday, December 21, 2025  2:00 AM 

Prepared by Bob Weisman, SCSU Meteorologist and Professor Emeritus

36 Hours of the Coldest Air in North America Ahead

This Air Mass is Cold, But Wed-Thurs Colder (Although Not Near Record Cold)

Yesterday was the coldest day of the season so far (see 30-day graph of St. Cloud temperatures from MesoWest) with a high of only 16 degrees (coldest since February 19). Yesterday's low was -4 degrees, the coldest low since February 21. That's the coldest that our current air mass, under the Kansas high (see yesterday's 3 PM NWS WPC North America zoom-in map), can support. However, there's another, even colder air mass now moving from Nunavut into northern Saskatchewan and Manitoba (see afternoon temperatures in the minus teens and minus 20s on yesterday's 3 PM NWS WPC North America zoom-in map; see areas of dark blue, air as cold as middle clouds, on the College of DuPage North America clean infrared satellite loop). That surge of cold air will push into south central Canada and the Great Lakes by tomorrow morning (see area of colder than average air, dark blue and purple, expand as it pushes southward on the 850 mb temperature anomaly map on the Alicia Bentley real-time GFS site). Most of Minnesota will dodge the coldest of the cold air, but we will have about 36 hours worth of the coldest air of the season so far. Temperatures will be in the 20's for much of tonight as the weak low pressure system on the leading edge of the next cold air surge will push some scattered thicker clouds into Minnesota (see College of DuPage North America shortwave infrared loop). There will only be a little bit of light snow (1 in 3 chance for accumulation of between a dusting and an inch) as the system goes by.

Then, the colder air will push in. Temperatures will be in the teens through much of tomorrow, then fall into the plus single digits. Temperatures will fall into the minus single digits, maybe -10 by early Thursday. Highs will only climb back to 10 on Thursday afternoon.

Becoming Milder Friday, Uncertain Beyond

With the coldest of the cold air headed for Quebec, the continued northwest-to-southeast flow (see College of DuPage North America water vapor loop) will alternate air that descended the Canadian Rockies and warmed (see yesterday afternoon's temperatures in central and southern Alberta on the NWS WPC North America zoom-in map) with more air from Nunavut and the Northwest Territories. However, the Wednesday-Thursday slab of cold air won't leave air as cold behind it, so even getting into the next cold air mass won't produce temperatures as cold as we will see during the middle of this week. The timing for each air mass is still uncertain, but my best guess is that high temperatures return to the 20's Friday, but fall back to the teens Saturday. We will continue to be near the boundary of these two air masses beyond Saturday, so the temperature is hard to pin down, but we have a better chance for below average temperatures on Sunday than average temperatures. Snowfall chances will be light with this parade of lows, but I am uncertain whether central Minnesota will have a shot of getting any snow from Saturday into early next week.

Still Quite Mild and Dry in November, Despite Last Week

The Thanksgiving Week snowstorms and the coldest air of the season still couldn't off-set a dry and warm rest of November (see St. Cloud November and Fall 2025 weather summary). That includes having the 8th warmest fall in St. Cloud records and the 10th driest August through November on record.

Detailed St. Cloud, MN, and Vicinity Forecast

Confidence Level: "The Bugs Are Waiting for Me to Mow the Lawn"

Tuesday 12/2/2025: Mixed sun and high clouds, but not quite as cold. Perhaps a stray snow flurry. High: between 18 and 23. Winds: SW 5-15 MPH. Chance of measurable snowfall: 20%.

Tuesday Night: Cloudy with a chance for light snow or flurries and not as cold. Any accumulation will be limited to between a dusting and an inch. Turning windy late at night. Temperatures holding in the 20's much of the night before dropping to between 12 and 17 by morning. Winds: SW 5-10 MPH evening, shifting to NW 10-20 MPH with higher gusts during the early morning hours. Some low visibility due to blowing snow in open areas. Chance of measurable snowfall: 30%.

Wednesday 12/3/2025: Mixed clouds and some sunny breaks (more sun during the afternoon) with a few flurries possible. Windy and turning colder during the afternoon. Low visibility due to blowing snow possible in open areas. Temperatures holding between 12 and 17 through midday, then falling into the plus single digits by late afternoon. Winds: NW 10-25 MPH. Wind chill: between -5 and +5 during the morning, between -15 and -5 during the afternoon. Chance of measurable snowfall: 10%.

Wednesday Night: Clear with diminishing wind and possibly the coldest night of the season so far. Low: between -10 and -4. Winds: NW 5 MPH, becoming SW during the early morning hours. Wind chill in the minus teens and -20s through midnight. Chance of measurable snowfall: 10%.

Thursday 12/4/2025: Sunshine through high clouds through midday. Cloudy during the afternoon with a slight chance for a snow flurry. Windy and continued cold. High: between 8 and 13. Winds: S 8-15 MPH during the morning, SW 15-25 MPH during the afternoon. Wind chill: between -20 and -5 during the morning, in the minus single digits during the afternoon. Chance of measurable snowfall: 20%.

Confidence Level: "Extra Bugs Will Come From Every Home on the Block to Hover Around My Head"

Thursday Night: Cloudy and not nearly as cold. A chance for a snow flurry. Temperatures holding in the teens. Winds: SW 5-10 MPH, becoming NW 5-10 MPH late. Chance of measurable snowfall: 20%.

Friday 12/5/2025: Cloudy, not as breezy, and not as cold. Maybe a snow flurry. High: between 20 and 25. Winds: NW 5-10 MPH. Chance of measurable snowfall: 20%.

Confidence Level: "Enough Bugs Will Fly into My Mouth to Throw Off My Diet

Friday Night: Partly clear and a bit colder. More clouds late at night. Low: between +4 and +10. Winds: N 5 MPH. Chance of measurable snowfall: 10%.

Saturday 12/6/2025: Cloudy, not as breezy, and colder. A chance of light snow or flurries. High: between 12 and 17. Winds: NW 5-10 MPH. Chance of measurable snowfall: 20%.

Extended: Continued colder than average through the weekend??? Uncertain chances for light snow????

Forecast Confidence (10 - "The Rabbits Will Thump Even Though I Fed Them"; 0 - "The Rabbits Will Offer To Groom My Bald Spot"): 8 Tuesday, 6 Tuesday night and Wednesday, 7 Wednesday night and Thursday, 5 Thursday night and Friday, 3 Friday night and Saturday, 1 Sunday.

Yesterday's High: 16°F; Overnight Low (through 2 AM Tuesday): 4°F;
St. Cloud Airport 24-Hour Melted Precipitation (through 2 AM Tuesday): Trace; SCSU 24-Hour Precipitation (through 2 AM Tuesday): Trace

Next Update: Wednesday, December 3, 2025 6 AM

Let me know what you think about this forecast and discussion by emailing SCSU meteorology professor Bob Weisman. Please note that I make the forecast, not the weather!

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