National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Winter Storm to Impact the Region Sunday Afternoon - Monday Morning

A strong winter storm moves through the region Sunday afternoon through Monday morning. The combination of moderate to heavy snow, strong northwest winds, and falling temperatures may lead to hazardous travel conditions for much of the area. The greatest impacts in Wisconsin are expected to be along and north of I-90, while blizzard conditions are possible west of the Mississippi River. Read More >

Hazardous Weather Conditions

Current conditions at

Sparta, Sparta / Fort McCoy Airport (KCMY)

Lat: 43.96°NLon: 90.74°WElev: 837ft.

Overcast

39°F

4°C

Humidity 98%
Wind Speed Calm
Barometer 29.73 in (1007.7 mb)
Dewpoint 39°F (4°C)
Visibility 9.00 mi
Last update 27 Dec 11:55 pm CST
Extended Forecast for

Ontario WI

Winter Weather Advisory December 28, 03:00pm until December 29, 12:00pm
Dense Fog Advisory December 28, 12:13am until December 28, 12:00pm
Click here for hazard details and duration
Winter Weather Advisory
Dense Fog Advisory
  •  
    Dense Fog Advisory December 28, 12:13am until December 28, 12:00pm

    NOW until 12:00pm Sun

    Dense Fog Advisory

  • Overnight

    Low: 36 °F

    Areas Drizzle
    and Dense Fog

  • Sunday

    Sunday: Snow, possibly mixed with rain, becoming all snow after 5pm. Widespread dense fog, mainly before 7am. Temperature falling to around 29 by 5pm. Light and variable wind becoming northwest 10 to 15 mph in the afternoon. Winds could gust as high as 34 mph. Chance of precipitation is 100%. New snow accumulation of less than one inch possible.

    High: 38 °F⇓

    Rain and
    Dense Fog
    then
    Rain/Snow

  • Sunday Night

    Sunday Night: Snow, mainly before 5am. The snow could be heavy at times. Widespread blowing snow, mainly between 8pm and 5am. Low around 11. Wind chill values as low as -5. Blustery, with a west wind 16 to 21 mph, with gusts as high as 46 mph. Chance of precipitation is 100%. New snow accumulation of 4 to 8 inches possible.

    Low: 11 °F

    Heavy Snow
    and Blowing
    Snow

  • Monday

    Monday: A 30 percent chance of snow before noon. Patchy blowing snow before 3pm. Partly sunny, with a high near 18. Wind chill values as low as -7. Blustery, with a northwest wind 15 to 23 mph, with gusts as high as 43 mph.

    High: 18 °F

    Chance Snow
    and Patchy
    Blowing Snow

  • Monday Night

    Monday Night: Mostly clear, with a low around 2. Northwest wind 5 to 13 mph, with gusts as high as 26 mph.

    Low: 2 °F

    Mostly Clear

  • Tuesday

    Tuesday: A 20 percent chance of snow after noon. Partly sunny, with a high near 26. West wind 5 to 8 mph, with gusts as high as 18 mph.

    High: 26 °F

    Partly Sunny
    then Slight
    Chance Snow

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 15. West wind 7 to 9 mph, with gusts as high as 20 mph.

    Low: 15 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: A 30 percent chance of snow after noon. Mostly cloudy, with a high near 24. Northwest wind around 8 mph, with gusts as high as 20 mph.

    High: 24 °F

    Mostly Cloudy
    then Chance
    Snow

Detailed Forecast

Overnight
Areas of drizzle before 4am. Widespread dense fog, mainly before 5am. Otherwise, cloudy, with a low around 36. Calm wind.
Sunday
Snow, possibly mixed with rain, becoming all snow after 5pm. Widespread dense fog, mainly before 7am. Temperature falling to around 29 by 5pm. Light and variable wind becoming northwest 10 to 15 mph in the afternoon. Winds could gust as high as 34 mph. Chance of precipitation is 100%. New snow accumulation of less than one inch possible.
Sunday Night
Snow, mainly before 5am. The snow could be heavy at times. Widespread blowing snow, mainly between 8pm and 5am. Low around 11. Wind chill values as low as -5. Blustery, with a west wind 16 to 21 mph, with gusts as high as 46 mph. Chance of precipitation is 100%. New snow accumulation of 4 to 8 inches possible.
Monday
A 30 percent chance of snow before noon. Patchy blowing snow before 3pm. Partly sunny, with a high near 18. Wind chill values as low as -7. Blustery, with a northwest wind 15 to 23 mph, with gusts as high as 43 mph.
Monday Night
Mostly clear, with a low around 2. Northwest wind 5 to 13 mph, with gusts as high as 26 mph.
Tuesday
A 20 percent chance of snow after noon. Partly sunny, with a high near 26. West wind 5 to 8 mph, with gusts as high as 18 mph.
Tuesday Night
Mostly cloudy, with a low around 15. West wind 7 to 9 mph, with gusts as high as 20 mph.
Wednesday
A 30 percent chance of snow after noon. Mostly cloudy, with a high near 24. Northwest wind around 8 mph, with gusts as high as 20 mph.
Wednesday Night
A 30 percent chance of snow before midnight. Mostly cloudy, with a low around 2. Northwest wind around 6 mph.
New Year's Day
Mostly sunny, with a high near 15. Northwest wind 5 to 7 mph.
Thursday Night
Mostly clear, with a low around -1. West wind around 5 mph becoming calm in the evening.
Friday
Partly sunny, with a high near 20. Calm wind becoming west around 6 mph.
Friday Night
Partly cloudy, with a low around 7. Light southwest wind.
Saturday
Mostly sunny, with a high near 27. Southeast wind 3 to 7 mph.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Ontario WI
 43.73°N 90.58°W
Last Update:
11:06 pm CST Dec 27, 2025
Forecast Valid:
12am CST Dec 28, 2025-6pm CST Jan 3, 2026
 
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Additional Resources

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High Temperature

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Chance of Precipitation