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

Sparta, Sparta / Fort McCoy Airport (KCMY)

Lat: 43.96°NLon: 90.74°WElev: 837ft.

Mostly Cloudy

63°F

17°C

Humidity 51%
Wind Speed W 12 mph
Barometer 29.82 in (1010.2 mb)
Dewpoint 44°F (7°C)
Visibility 10.00 mi
Last update 12 May 8:55 pm CDT
Extended Forecast for

Ontario WI

  • Tonight

    Tonight: Partly cloudy, with a low around 47. Northwest wind 9 to 14 mph, with gusts as high as 31 mph.

    Low: 47 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 68. North wind 10 to 15 mph, with gusts as high as 24 mph.

    High: 68 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Clear, with a low around 39. North wind 5 to 7 mph becoming calm in the evening.

    Low: 39 °F

    Clear

  • Thursday

    Thursday: Sunny, with a high near 72. Light southeast wind becoming south 5 to 10 mph in the morning. Winds could gust as high as 20 mph.

    High: 72 °F

    Sunny

  • Thursday Night

    Thursday Night: Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 51. South wind 7 to 10 mph, with gusts as high as 25 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    Low: 51 °F

    Showers
    Likely

  • Friday

    Friday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 82. Southwest wind around 10 mph, with gusts as high as 22 mph.

    High: 82 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Friday Night

    Friday Night: A 20 percent chance of showers and thunderstorms before 1am. Mostly clear, with a low around 54. Southwest wind around 5 mph becoming calm in the evening.

    Low: 54 °F

    Slight Chance
    T-storms

  • Saturday

    Saturday: Sunny, with a high near 82. Calm wind becoming west 5 to 8 mph in the morning.

    High: 82 °F

    Sunny

  • Saturday Night

    Saturday Night: A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 53. Calm wind becoming east around 5 mph after midnight.

    Low: 53 °F

    Chance
    Showers

Detailed Forecast

Tonight
Partly cloudy, with a low around 47. Northwest wind 9 to 14 mph, with gusts as high as 31 mph.
Wednesday
Mostly sunny, with a high near 68. North wind 10 to 15 mph, with gusts as high as 24 mph.
Wednesday Night
Clear, with a low around 39. North wind 5 to 7 mph becoming calm in the evening.
Thursday
Sunny, with a high near 72. Light southeast wind becoming south 5 to 10 mph in the morning. Winds could gust as high as 20 mph.
Thursday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 51. South wind 7 to 10 mph, with gusts as high as 25 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Friday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 82. Southwest wind around 10 mph, with gusts as high as 22 mph.
Friday Night
A 20 percent chance of showers and thunderstorms before 1am. Mostly clear, with a low around 54. Southwest wind around 5 mph becoming calm in the evening.
Saturday
Sunny, with a high near 82. Calm wind becoming west 5 to 8 mph in the morning.
Saturday Night
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 53. Calm wind becoming east around 5 mph after midnight.
Sunday
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Partly sunny, with a high near 80. East wind 7 to 14 mph, with gusts as high as 24 mph. Chance of precipitation is 60%.
Sunday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 59. Southeast wind 7 to 9 mph, with gusts as high as 22 mph. Chance of precipitation is 70%.
Monday
Showers likely. Partly sunny, with a high near 80. Southwest wind 9 to 15 mph, with gusts as high as 24 mph. Chance of precipitation is 60%.
Monday Night
A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 54. West wind 5 to 8 mph, with gusts as high as 20 mph.
Tuesday
A 20 percent chance of showers. Mostly sunny, with a high near 75. Northwest wind 5 to 8 mph.
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ABOUT THIS FORECAST

 
Point Forecast:
Ontario WI
 43.73°N 90.58°W
Last Update:
9:27 pm CDT May 12, 2026
Forecast Valid:
9pm CDT May 12, 2026-6pm CDT May 19, 2026
 
Forecast Discussion
 
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Additional Resources

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Hourly Weather Forecast

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High Temperature

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Chance of Precipitation