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.

Mostly Cloudy

59°F

15°C

Humidity 93%
Wind Speed Calm
Barometer 30.15 in (1021.4 mb)
Dewpoint 57°F (14°C)
Visibility 8.00 mi
Last update 18 Sep 6:55 pm CDT
Extended Forecast for

Ontario WI

Flood Watch until September 19, 01:00pm
Click here for hazard details and duration
Flood Watch
  •  
    Flood Watch until September 19, 01:00pm

    NOW until 1:00pm Sat

    Flood Watch

  • Tonight

    Low: 54 °F

    Heavy Rain

  • Saturday

    Saturday: Showers and possibly a thunderstorm before 9am, then a chance of showers and thunderstorms between 9am and noon, then showers likely and possibly a thunderstorm after noon. High near 70. East wind 7 to 11 mph, with gusts as high as 20 mph. Chance of precipitation is 80%. New rainfall amounts between 1 and 2 inches possible.

    High: 70 °F

    Showers

  • Saturday Night

    Saturday Night: Showers, mainly before 8pm. Low around 52. Northeast wind 5 to 7 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 52 °F

    Showers then
    Chance
    Showers

  • Sunday

    Sunday: A 10 percent chance of showers before 7am. Partly sunny, with a high near 69. Northeast wind 8 to 13 mph, with gusts as high as 22 mph.

    High: 69 °F

    Slight Chance
    Showers then
    Partly Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 47. Northeast wind 7 to 9 mph, with gusts as high as 22 mph.

    Low: 47 °F

    Mostly Cloudy

  • Monday

    Monday: A 30 percent chance of showers after 1pm. Mostly cloudy, with a high near 64. East wind 7 to 11 mph, with gusts as high as 20 mph.

    High: 64 °F

    Mostly Cloudy
    then Chance
    Showers

  • Monday Night

    Monday Night: A 20 percent chance of showers. Mostly cloudy, with a low around 43. East wind 3 to 8 mph. Winds could gust as high as 18 mph.

    Low: 43 °F

    Slight Chance
    Showers

  • Tuesday

    Tuesday: Partly sunny, with a high near 63. East wind 3 to 8 mph.

    High: 63 °F

    Partly Sunny

Detailed Forecast

Tonight
Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 54. East wind 10 to 15 mph, with gusts as high as 28 mph. Chance of precipitation is 90%. New rainfall amounts between 2 and 3 inches possible.
Saturday
Showers and possibly a thunderstorm before 9am, then a chance of showers and thunderstorms between 9am and noon, then showers likely and possibly a thunderstorm after noon. High near 70. East wind 7 to 11 mph, with gusts as high as 20 mph. Chance of precipitation is 80%. New rainfall amounts between 1 and 2 inches possible.
Saturday Night
Showers, mainly before 8pm. Low around 52. Northeast wind 5 to 7 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.
Sunday
A 10 percent chance of showers before 7am. Partly sunny, with a high near 69. Northeast wind 8 to 13 mph, with gusts as high as 22 mph.
Sunday Night
Mostly cloudy, with a low around 47. Northeast wind 7 to 9 mph, with gusts as high as 22 mph.
Monday
A 30 percent chance of showers after 1pm. Mostly cloudy, with a high near 64. East wind 7 to 11 mph, with gusts as high as 20 mph.
Monday Night
A 20 percent chance of showers. Mostly cloudy, with a low around 43. East wind 3 to 8 mph. Winds could gust as high as 18 mph.
Tuesday
Partly sunny, with a high near 63. East wind 3 to 8 mph.
Tuesday Night
Mostly clear, with a low around 42. Light east wind.
Wednesday
Mostly sunny, with a high near 67. Calm wind becoming east around 5 mph.
Wednesday Night
Partly cloudy, with a low around 45. Calm wind.
Thursday
Partly sunny, with a high near 70. Calm wind.
Thursday Night
Partly cloudy, with a low around 47. Calm wind.
Friday
Mostly sunny, with a high near 72. Calm wind.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Ontario WI
 43.73°N 90.58°W
Last Update:
6:16 pm CDT Sep 18, 2026
Forecast Valid:
7pm CDT Sep 18, 2026-6pm CDT Sep 25, 2026
 
Forecast Discussion
 
Get as KML Get as XML

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