National Weather Service Forecast for: Janesville WI
Issued by: National Weather Service Milwaukee, WI
Updated: 2:41 pm CDT Jul 16, 2026
 
This
Afternoon
This Afternoon: Isolated showers, with thunderstorms also possible after 4pm. Areas of smoke. Partly sunny and hot, with a high near 91. Heat index values as high as 97. Southeast wind around 5 mph. Chance of precipitation is 20%.
Isolated
T-storms
 Tonight

Tonight: Isolated showers and thunderstorms before 9pm. Widespread smoke, mainly after 4am. Mostly cloudy, with a low around 67. Southeast wind around 5 mph becoming calm after midnight. Chance of precipitation is 20%.
Isolated
T-storms then
Smoke
 Friday

Friday: Scattered showers and thunderstorms, mainly after 5pm. Widespread smoke, mainly before 9am. Mostly sunny and hot, with a high near 90. Heat index values as high as 96. Light south wind becoming southwest 5 to 10 mph in the morning. Chance of precipitation is 30%.
Smoke then
Scattered
T-storms
 Friday
Night
Friday Night: Isolated showers and thunderstorms before 7pm. Mostly clear, with a low around 72. Southwest wind around 5 mph. Chance of precipitation is 10%.
Isolated
T-storms then
Mostly Clear
 Saturday

Saturday: Isolated showers and thunderstorms between 1pm and 4pm, then isolated showers after 4pm. Sunny, with a high near 89. West wind around 10 mph becoming north in the afternoon. Chance of precipitation is 20%.
Mostly Sunny
then Isolated
T-storms
 Saturday
Night
Saturday Night: Mostly clear, with a low around 62. North wind 5 to 10 mph becoming light and variable in the evening.
Mostly Clear

 Sunday

Sunday: Sunny, with a high near 84. Calm wind becoming east around 5 mph.
Sunny

 Sunday
Night
Sunday Night: Partly cloudy, with a low around 64. South wind around 5 mph becoming calm.
Partly Cloudy

 Monday

Monday: A 30 percent chance of showers and thunderstorms, mainly before 1pm. Partly sunny, with a high near 87.
Chance
Showers
Hi 91 °F Lo 67 °F Hi 90 °F Lo 72 °F Hi 89 °F Lo 62 °F Hi 84 °F Lo 64 °F Hi 87 °F

Hazardous Weather Outlook
Air Quality Alert
 

This Afternoon
 
 Isolated showers, with thunderstorms also possible after 4pm. Areas of smoke. Partly sunny and hot, with a high near 91. Heat index values as high as 97. Southeast wind around 5 mph. Chance of precipitation is 20%.
Tonight
 
 Isolated showers and thunderstorms before 9pm. Widespread smoke, mainly after 4am. Mostly cloudy, with a low around 67. Southeast wind around 5 mph becoming calm after midnight. Chance of precipitation is 20%.
Friday
 
 Scattered showers and thunderstorms, mainly after 5pm. Widespread smoke, mainly before 9am. Mostly sunny and hot, with a high near 90. Heat index values as high as 96. Light south wind becoming southwest 5 to 10 mph in the morning. Chance of precipitation is 30%.
Friday Night
 
 Isolated showers and thunderstorms before 7pm. Mostly clear, with a low around 72. Southwest wind around 5 mph. Chance of precipitation is 10%.
Saturday
 
 Isolated showers and thunderstorms between 1pm and 4pm, then isolated showers after 4pm. Sunny, with a high near 89. West wind around 10 mph becoming north in the afternoon. Chance of precipitation is 20%.
Saturday Night
 
 Mostly clear, with a low around 62. North wind 5 to 10 mph becoming light and variable in the evening.
Sunday
 
 Sunny, with a high near 84. Calm wind becoming east around 5 mph.
Sunday Night
 
 Partly cloudy, with a low around 64. South wind around 5 mph becoming calm.
Monday
 
 A 30 percent chance of showers and thunderstorms, mainly before 1pm. Partly sunny, with a high near 87.
Monday Night
 
 A chance of showers and thunderstorms before 1am, then a slight chance of showers. Partly cloudy, with a low around 68. Chance of precipitation is 40%.
Tuesday
 
 A 20 percent chance of showers. Sunny, with a high near 83.
Tuesday Night
 
 Mostly clear, with a low around 59.
Wednesday
 
 Sunny, with a high near 79.
Wednesday Night
 
 Mostly clear, with a low around 57.
Thursday
 
 Sunny, with a high near 81.

 

Forecast from NOAA-NWS for Janesville WI.