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.

Fair

61°F

16°C

Humidity 82%
Wind Speed Calm
Barometer 29.95 in (1014.5 mb)
Dewpoint 55°F (13°C)
Visibility 10.00 mi
Last update 24 May 8:55 pm CDT
Extended Forecast for

Ontario WI

  • Tonight

    Tonight: A slight chance of showers between 4am and 5am. Partly cloudy, with a low around 57. South wind 3 to 6 mph. Chance of precipitation is 20%.

    Low: 57 °F

    Mostly Clear
    then Slight
    Chance
    Showers

  • Memorial Day

    Memorial Day: A 40 percent chance of showers, mainly before noon. Mostly cloudy, then gradually becoming sunny, with a high near 83. Southwest wind 5 to 15 mph, with gusts as high as 24 mph.

    High: 83 °F

    Chance
    Showers

  • Monday Night

    Monday Night: Mostly clear, with a low around 61. South wind 5 to 9 mph becoming light. Winds could gust as high as 20 mph.

    Low: 61 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny, with a high near 88. Southwest wind 3 to 6 mph.

    High: 88 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 60. Calm wind.

    Low: 60 °F

    Mostly Clear

  • Wednesday

    Wednesday: A 30 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 88. Calm wind.

    High: 88 °F

    Sunny then
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 56. Light east wind.

    Low: 56 °F

    Partly Cloudy

  • Thursday

    Thursday: Sunny, with a high near 83. East wind 3 to 5 mph.

    High: 83 °F

    Sunny

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 55. Calm wind.

    Low: 55 °F

    Partly Cloudy

Detailed Forecast

Tonight
A slight chance of showers between 4am and 5am. Partly cloudy, with a low around 57. South wind 3 to 6 mph. Chance of precipitation is 20%.
Memorial Day
A 40 percent chance of showers, mainly before noon. Mostly cloudy, then gradually becoming sunny, with a high near 83. Southwest wind 5 to 15 mph, with gusts as high as 24 mph.
Monday Night
Mostly clear, with a low around 61. South wind 5 to 9 mph becoming light. Winds could gust as high as 20 mph.
Tuesday
Sunny, with a high near 88. Southwest wind 3 to 6 mph.
Tuesday Night
Mostly clear, with a low around 60. Calm wind.
Wednesday
A 30 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 88. Calm wind.
Wednesday Night
Partly cloudy, with a low around 56. Light east wind.
Thursday
Sunny, with a high near 83. East wind 3 to 5 mph.
Thursday Night
Partly cloudy, with a low around 55. Calm wind.
Friday
Mostly sunny, with a high near 81. Light southeast wind.
Friday Night
Partly cloudy, with a low around 56. Calm wind.
Saturday
Mostly sunny, with a high near 79. Calm wind becoming east around 6 mph in the afternoon.
Saturday Night
Partly cloudy, with a low around 54. Calm wind.
Sunday
Mostly sunny, with a high near 79. Calm wind becoming east around 5 mph in the afternoon.
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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:
6:07 pm CDT May 24, 2026
Forecast Valid:
9pm CDT May 24, 2026-6pm CDT May 31, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation