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

Hazardous Weather Conditions

Current conditions at

Sparta, Sparta / Fort McCoy Airport (KCMY)

Lat: 43.96°NLon: 90.74°WElev: 837ft.

N/A

Humidity NA
Wind Speed NA
Barometer NA
Dewpoint N/A
Visibility NA
Last update *** Not a current observation ***
Extended Forecast for

Ontario WI

  • Tonight

    Tonight: A 10 percent chance of showers and thunderstorms after 5am. Partly cloudy, with a low around 47. Light east wind.

    Low: 47 °F

    Mostly Cloudy
    then Slight
    Chance
    T-storms

  • Tuesday

    Tuesday: A chance of showers and thunderstorms before 2pm, then a slight chance of showers after 5pm. Partly sunny, with a high near 61. Light and variable wind becoming north 6 to 11 mph in the morning. Winds could gust as high as 21 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    High: 61 °F

    Chance
    T-storms then
    Chance
    Showers

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 31. North wind 6 to 10 mph, with gusts as high as 21 mph.

    Low: 31 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: A chance of snow showers after 1pm, mixing with rain after 4pm. Mostly cloudy, with a high near 43. East wind 6 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 30%.

    High: 43 °F

    Partly Sunny
    then Chance
    Rain/Snow

  • Wednesday Night

    Wednesday Night: Rain showers and freezing rain, possibly mixed with snow showers. Low around 30. East wind 11 to 13 mph, with gusts as high as 25 mph. Chance of precipitation is 90%. New ice accumulation of 0.1 to 0.2 of an inch possible. New snow accumulation of 1 to 2 inches possible.

    Low: 30 °F

    Wintry Mix

  • Thursday

    Thursday: Rain, possibly mixed with snow showers, becoming all rain after 7am. High near 49. East wind 11 to 15 mph, with gusts as high as 28 mph. Chance of precipitation is 100%. New snow accumulation of less than a half inch possible.

    High: 49 °F

    Rain/Snow
    then Showers

  • Thursday Night

    Thursday Night: A 50 percent chance of showers, mainly before 1am. Mostly cloudy, with a low around 31. East wind 7 to 10 mph becoming west in the evening. Winds could gust as high as 20 mph.

    Low: 31 °F

    Chance
    Showers

  • Friday

    Friday: A 30 percent chance of showers after 1pm. Partly sunny, with a high near 52. Northwest wind 5 to 8 mph becoming east in the afternoon.

    High: 52 °F

    Partly Sunny
    then Chance
    Showers

  • Friday Night

    Friday Night: Showers likely and possibly a thunderstorm, then showers after 1am. Low around 35. East wind 9 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 80%.

    Low: 35 °F

    Showers

Detailed Forecast

Tonight
A 10 percent chance of showers and thunderstorms after 5am. Partly cloudy, with a low around 47. Light east wind.
Tuesday
A chance of showers and thunderstorms before 2pm, then a slight chance of showers after 5pm. Partly sunny, with a high near 61. Light and variable wind becoming north 6 to 11 mph in the morning. Winds could gust as high as 21 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Tuesday Night
Mostly cloudy, with a low around 31. North wind 6 to 10 mph, with gusts as high as 21 mph.
Wednesday
A chance of snow showers after 1pm, mixing with rain after 4pm. Mostly cloudy, with a high near 43. East wind 6 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 30%.
Wednesday Night
Rain showers and freezing rain, possibly mixed with snow showers. Low around 30. East wind 11 to 13 mph, with gusts as high as 25 mph. Chance of precipitation is 90%. New ice accumulation of 0.1 to 0.2 of an inch possible. New snow accumulation of 1 to 2 inches possible.
Thursday
Rain, possibly mixed with snow showers, becoming all rain after 7am. High near 49. East wind 11 to 15 mph, with gusts as high as 28 mph. Chance of precipitation is 100%. New snow accumulation of less than a half inch possible.
Thursday Night
A 50 percent chance of showers, mainly before 1am. Mostly cloudy, with a low around 31. East wind 7 to 10 mph becoming west in the evening. Winds could gust as high as 20 mph.
Friday
A 30 percent chance of showers after 1pm. Partly sunny, with a high near 52. Northwest wind 5 to 8 mph becoming east in the afternoon.
Friday Night
Showers likely and possibly a thunderstorm, then showers after 1am. Low around 35. East wind 9 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 80%.
Saturday
Showers likely. Mostly cloudy, with a high near 48. Northeast wind 10 to 15 mph becoming northwest in the afternoon. Chance of precipitation is 70%.
Saturday Night
A chance of rain and snow showers. Mostly cloudy, with a low around 29. West wind 11 to 13 mph, with gusts as high as 22 mph. Chance of precipitation is 40%.
Sunday
Partly sunny, with a high near 47. Northwest wind 10 to 14 mph, with gusts as high as 22 mph.
Sunday Night
Partly cloudy, with a low around 27. Northwest wind 5 to 8 mph becoming south after midnight.
Monday
Mostly sunny, with a high near 54. Southwest wind 5 to 11 mph.
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ABOUT THIS FORECAST

 
Point Forecast:
Ontario WI
 43.73°N 90.58°W
Last Update:
9:27 pm CDT Mar 30, 2026
Forecast Valid:
9pm CDT Mar 30, 2026-6pm CDT Apr 6, 2026
 
Forecast Discussion
 
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Additional Resources

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Hourly Weather Forecast

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation