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

Areas of Dangerous Heat and Heavy Rain with Possible Flooding into this Weekend

Hot temperatures and high humidity are forecast to continue across the mid-Mississippi Valley into this weekend with heat advisories in effect. Heavy to excessive rainfall occurring at times through Sunday could bring areas of flooding to parts of the upper Midwest, central Great Lakes, southern New England and Virginia/North Carolina tidewater region. Read More >

Hazardous Weather Conditions

Current conditions at

Janesville-Rock County (KJVL)

Lat: 42.62°NLon: 89.04°WElev: 801ft.

Fair

59°F

15°C

Humidity 100%
Wind Speed NE 3 mph
Barometer 30.27 in
Dewpoint 59°F (15°C)
Visibility 10.00 mi
Last update 18 Sep 4:35 am CDT
Extended Forecast for

Janesville WI

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

  • Today

    Today: A 20 percent chance of showers after 4pm. Mostly cloudy, with a high near 71. East wind 5 to 10 mph increasing to 10 to 15 mph in the afternoon.

    High: 71 °F

    Partly Sunny
    then Slight
    Chance
    Showers

  • Tonight

    Tonight: A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1am. Some of the storms could produce heavy rainfall. Low around 57. East wind 10 to 15 mph. Chance of precipitation is 90%. New rainfall amounts between 1 and 2 inches possible.

    Low: 57 °F

    Chance
    Showers then
    Heavy Rain

  • Saturday

    Saturday: Showers and possibly a thunderstorm before noon, then a chance of showers and thunderstorms between noon and 3pm, then showers likely and possibly a thunderstorm after 3pm. High near 70. East wind 10 to 15 mph. Chance of precipitation is 90%. New rainfall amounts between 1 and 2 inches possible.

    High: 70 °F

    Showers then
    Showers
    Likely

  • Saturday Night

    Saturday Night: Showers and possibly a thunderstorm. Low around 57. Northeast wind 5 to 10 mph. Chance of precipitation is 80%. New rainfall amounts between three quarters and one inch possible.

    Low: 57 °F

    Showers

  • Sunday

    Sunday: Showers likely, mainly before 1pm. Mostly cloudy, with a high near 64. Northeast wind 10 to 15 mph. Chance of precipitation is 60%. New precipitation amounts between a quarter and half of an inch possible.

    High: 64 °F

    Showers
    Likely

  • Sunday Night

    Sunday Night: A 40 percent chance of showers after 1am. Cloudy, with a low around 50. Northeast wind around 15 mph.

    Low: 50 °F

    Mostly Cloudy
    then Chance
    Showers

  • Monday

    Monday: A 50 percent chance of showers. Cloudy, with a high near 60. Northeast wind around 15 mph, with gusts as high as 25 mph.

    High: 60 °F

    Chance
    Showers

  • Monday Night

    Monday Night: A 20 percent chance of showers. Mostly cloudy, with a low around 46. Northeast wind 10 to 15 mph.

    Low: 46 °F

    Slight Chance
    Showers

  • Tuesday

    Tuesday: A 20 percent chance of showers before 1pm. Mostly cloudy, with a high near 60.

    High: 60 °F

    Slight Chance
    Showers

Detailed Forecast

Today
A 20 percent chance of showers after 4pm. Mostly cloudy, with a high near 71. East wind 5 to 10 mph increasing to 10 to 15 mph in the afternoon.
Tonight
A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1am. Some of the storms could produce heavy rainfall. Low around 57. East wind 10 to 15 mph. Chance of precipitation is 90%. New rainfall amounts between 1 and 2 inches possible.
Saturday
Showers and possibly a thunderstorm before noon, then a chance of showers and thunderstorms between noon and 3pm, then showers likely and possibly a thunderstorm after 3pm. High near 70. East wind 10 to 15 mph. Chance of precipitation is 90%. New rainfall amounts between 1 and 2 inches possible.
Saturday Night
Showers and possibly a thunderstorm. Low around 57. Northeast wind 5 to 10 mph. Chance of precipitation is 80%. New rainfall amounts between three quarters and one inch possible.
Sunday
Showers likely, mainly before 1pm. Mostly cloudy, with a high near 64. Northeast wind 10 to 15 mph. Chance of precipitation is 60%. New precipitation amounts between a quarter and half of an inch possible.
Sunday Night
A 40 percent chance of showers after 1am. Cloudy, with a low around 50. Northeast wind around 15 mph.
Monday
A 50 percent chance of showers. Cloudy, with a high near 60. Northeast wind around 15 mph, with gusts as high as 25 mph.
Monday Night
A 20 percent chance of showers. Mostly cloudy, with a low around 46. Northeast wind 10 to 15 mph.
Tuesday
A 20 percent chance of showers before 1pm. Mostly cloudy, with a high near 60.
Tuesday Night
Partly cloudy, with a low around 46.
Wednesday
Partly sunny, with a high near 64.
Wednesday Night
Mostly cloudy, with a low around 46.
Thursday
Partly sunny, with a high near 67.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Janesville WI
 42.67°N 89.01°W (Elev. 797 ft)
Last Update:
4:36 am CDT Sep 18, 2026
Forecast Valid:
4am CDT Sep 18, 2026-6pm CDT Sep 24, 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