Saturday, December 13, 2025  2:20 AM 

Prepared by Bob Weisman, SCSU Meteorologist and Professor Emeritus

There is Beauty in the Cold

I liked seeing a StarTribune article about the good side of snow yesterday. All the snowmobilers, snowboarders, and skiers have been rejoicing. There is still a little worry about the ice thickness along snowmobile trails, since the Thanksgiving week snow storms happened before the ground had completely frozen, so experts had some caution that all trails were not open yet. But, the ice fishing resorts in northern Minnesota are seeing good ice.

There is more beauty in this cold air outbreak. The deep snow pack over central and southern Minnesota and the current winds will suspend some snow flakes in the air. As long as we are sunny during the first few hours after sunrise and the first couple of hours before sunset, we will have the opportunity to see sundogs, bright spots either side of the sun when the sun is close to the horizon (the video talks about this effect from cirrus clouds, but the blowing snow will provide us with those necessary ice crystals trapped in the air). Sun pillars, columns of bright light above the sun, are also possible. In yesterday morning's falling snow, I saw pillars above several street lights as the falling snow allowed reflection of the artificial light.

These effects may not happen in the southern half of Minnesota this morning, since the northern edge of the clouds (see College of DuPage North America clean infrared satellite loop) from the storm system due to pass to our southwest (potential for between 2 and 4 inches of snow from Sioux Falls into northwestern Iowa, and possibly brushing southwestern Minnesota; set tab to 00 UTC Sunday, 6 PM CST Saturday, on the NWS WPC probabilistic winter precipitation guidance), but most of Minnesota will have a better shot at clear sky approaching sunset.

And, we also had riming yesterday morning on the trees, since the very light snow we had early yesterday morning began with a period of fog and freezing drizzle. This is possible because water droplets in the atmosphere do not freeze at temperatures below freezing. They can be suspended as water droplets as long as the cloud doesn't have a temperature colder than 10 degrees. This happened before the deeper clouds producing the light snow came in. However, these 'supercooled' water droplets will instantly freeze on any surface they encounter. Those tree branches provided the perfect surface for those water droplets to freeze, producing the coating of rime. It is also a problem if an airplane flies through a cloud of these sub-freezing water droplets, since the rime will form on the plane. If the icing is severe, enough will build up on the plane to change the shape of the wing, which disrupts the proper air flow around the wing, so the plane will lose its lifting force.

So, Here's the Serious Part of the Cold

The National Weather Service cold weather advisory is in effect from the eastern Dakotas through Minnesota into Iowa, Wisconsin, and all the way to Tennessee and Alabama. In Minnesota, the advisory extends until 10 AM as some wind chills will be in the -30 to -25 range. Parts of eastern North Dakota and northwestern Minnesota have an extreme cold warning (dark blue), since some wind chills will be in the -40 to -35 range. Keep in mind that exposed skin can freeze in 30 minutes or less at wind chills of -25 or colder. That time drops to 10 minutes or less for wind chills of -35 or colder. If you go out, you should wear clothing that covers all exposed skin. More importantly, don't get yourself into a situation that requires you to be outside for long periods of time. Any pre-Christmas or holiday activity should include packing that cold weather supply kit in your vehicle.

Temperatures during the early morning are in the minus single digits in east central and southern Minnesota with minus teens north and east of Hwy. 210 (see NWS Aviation Weather Center METAR map) and those colder temperatures will work their way southward. Throw in the northwest wind blowing at 8-18 MPH and wind chills are already in the low minus teens and -20's in much of southern and central Minnesota with -30's in the area with the extreme cold warning (see NWS Minnesota hourly weather round-up).

The scenario for the cold is the same. We will have highs near or below zero today with those -35 to -20 wind chills persisting through the morning and only easing to -30 to -15 this afternoon. Tonight, the high pressure area will make its closest approach to Minnesota (see 00Z and 12Z Sunday, 6 PM Saturday night and 6 AM Sunday CST, tabs on the NWS WPC short-range forecast). That will lighten the winds, but only the Dakotas underneath the cold high will have a shot at those -30's or -40's temperatures that were in Alberta yesterday morning. In southern and central Minnesota, we will have the winds ease off, but they will still blow at 5-10 MPH during the evening. Temperatures will quickly fall to the minus teens, so there will be wind chills in the -20's and -30's. Late at night, we will have very light winds, which will give us a shot at our first low in the -20's since February 18 or January 20-21. If the light breeze stays up, which is likely to our north, temperatures will hang in the minus teens, but wind chills will be in the -40 to -25 range.

Tomorrow, the winds will be light through the morning as the arctic high pulls away. Temperatures will creep back into the minus single digits, possibly approaching zero by late in the day.

You can use the following links to track the cold:

• NWS Aviation Weather Center METAR map for temperatures, visibility, and snowfall
• NWS Minnesota hourly weather round-up for temperatures, wind speeds, and wind chill
• NWS Minnesota watch-warning map for cold weather advisory statements (also there will be winter weather advisories in South Dakota and perhaps extreme southwest Minnesota for potential 2-4 inch snow tomorrow).
• NWS cold weather safety page, including indoor and outdoor steps

The changing pressure followed by the high has been irritating my wife, Janet, who has joints sensitive to pressure changes. This will continue through Sunday. Also, the persistent winds are blowing some of the loose snow over roads in open areas. There are scattered areas of snow cover on main roads (see MnDOT Minnesota road reports), so expect the secondary local roads to have icy spots in exposed areas.

Just Keep Saying 40 by Tuesday....

However, Sunday evening will begin the moderating trend, which will get quite strong by Tuesday and Wednesday. Temperatures will slowly climb through the plus single digits, reaching near 10 by Monday morning. Afternoon highs on Monday will climb into the 20's. We will only see temperatures drop into the teens on Monday night, then we are likely to see above freezing highs both Tuesday and Wednesday. Tuesday will have more sunshine, so we have a shot at a 40 degree high. I've been dangling the idea of a 40 degree high on Tuesday to anyone who has been complaining to me about this weekend's cold.

There is a possibility of a Wednesday storm, but the track of that storm differs by a state in the long-range forecasts. This system will likely have frozen precipitation on its northern flank and the bulk of the precipitation on that side, but the wildly varying storm tracks puts central Minnesota on either side of the storm. The computer forecasts show a more active pattern for the second half of next week, so I can't even speculate about how warm or cold we will be. However, the early signs are that we will be much closer to average temperatures than we have been so far in December.

Detailed St. Cloud, MN, and Vicinity Forecast

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

Saturday 12/13/2025: Partly to mostly sunny, a painful breeze, and likely the coldest day of the season thus far. High: between -5 and 0. (record cold high: -3 in 1985). Winds: NW 10-20 MPH. Wind chill: between -38 and -20 during the morning, between -28 and -15 during the afternoon. Chance of measurable snowfall: 10%.

Saturday Night: Mostly clear, light winds, and likely the coldest night of the season so far. Serious wind chills during the evening. Low: between -23 and -15. Winds: NW 5-10 MPH evening, light late at night. Spotty wind chill: between -40 and -25. Chance of measurable snowfall: 0%.

Sunday 12/14/2025: Sunshine through afternoon high clouds, a biting afternoon breeze, and still quite cold. High: between -3 and +3. Winds: light early, SE 5-15 MPH during the afternoon. Wind chill: between -30 and -13. Chance of measurable snowfall: 10%.

Sunday Night: Partly clear, breezy, and not as cold. Temperatures holding in the plus single digits through the evening, reaching the low teens by morning. Winds: SE 5-15 MPH early evening, SW 8-15 MPH midnight and early morning hours. Wind chill: between -20 and -5 early evening, rising to between -15 and +5 during the early morning hours. Chance of measurable snowfall: 10%.

Monday 12/15/2025: Sunshine through high clouds, light winds, and seasonably cold. High: between 20 and 25. Winds: SW 5-15 MPH during the morning, becoming NW 8-15 MPH midday and afternoon. Chance of measurable snowfall: 10%.

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

Monday Night: Cloudy with some fog possible late. breezy, and seasonably cold. Temperatures between 10 and 15 by midnight, rising into the 20's during the early morning hours. Winds: light evening, S 5-15 MPH during the early morning hours. Chance of measurable snowfall: 10%.

Tuesday 12/16/2025: Sunshine through high clouds, breezy, and much milder. High: between 35 and 43. Winds: SW 8-15 MPH. Chance of measurable snowfall: 10%.

Tuesday Night: Partly clear, breezy, and seasonably cold. Low: between 20 and 25. Winds: SW 5-10 MPH evening, NW 8-15 MPH during the early morning hours. Chance of measurable snowfall: 10%.

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

Wednesday 12/17/2025: Cloudy, breezy, and still mild with a chance for snow or rain showers during the afternoon. High: between 30 and 38. Winds: SW 8-15 MPH. Chance of measurable precipitation: 30%.

Extended: Uncertain precipitation threat Wednesday night and Thursday??? Uncertain temperatures Thursday and Friday, but closer to average than recently???

Forecast Confidence (10 - "The Rabbits Will Thump Even Though I Fed Them"; 0 - "The Rabbits Will Offer To Groom My Bald Spot"): 8 Saturday, 7 Saturday night through Monday, 5 Monday night through Tuesday night, 2 Wednesday.

Yesterday's High: 18°F; Overnight Low (through 2 AM Saturday): -7°F; Top Wind Gust: 33 MPH at 11:44 AM and 3:46 PM Friday;
St. Cloud Airport 24-Hour Melted Precipitation (through 2 AM Saturday): 0.01 inch; SCSU 24-Hour Precipitation (through 2 AM Saturday): 0.01 inch/0.1 inch snow; Coldest Wind Chill (through 2 AM Saturday): -25°F 8-9 PM Friday

Next Update: Sunday, December 14, 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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