National Weather Service Forecast for: Janesville WI
Issued by: National Weather Service Milwaukee, WI
Updated: 6:37 am CDT May 26, 2026
 
Today

Today: Mostly sunny, with a high near 88. Southwest wind around 5 mph.
Mostly Sunny

 Tonight

Tonight: Partly cloudy, with a low around 59. Southwest wind around 5 mph becoming calm.
Partly Cloudy

 Wednesday

Wednesday: A slight chance of showers between noon and 1pm, then a chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 87. Calm wind becoming north around 5 mph in the afternoon. Chance of precipitation is 30%.
Mostly Sunny
then Chance
T-storms
 Wednesday
Night
Wednesday Night: A chance of thunderstorms before 7pm. Mostly clear, with a low around 52. Northeast wind around 10 mph. Chance of precipitation is 30%.
Chance
T-storms then
Mostly Clear
 Thursday

Thursday: Sunny, with a high near 75. East wind around 10 mph.
Sunny

 Thursday
Night
Thursday Night: Mostly clear, with a low around 48. East wind 5 to 10 mph becoming light and variable in the evening.
Mostly Clear

 Friday

Friday: Sunny, with a high near 82. Calm wind becoming northeast around 5 mph in the afternoon.
Sunny

 Friday
Night
Friday Night: Mostly clear, with a low around 53. East wind around 5 mph becoming calm.
Mostly Clear

 Saturday

Saturday: Sunny, with a high near 78.
Sunny
Hi 88 °F Lo 59 °F Hi 87 °F Lo 52 °F Hi 75 °F Lo 48 °F Hi 82 °F Lo 53 °F Hi 78 °F

Hazardous Weather Outlook
 

Today
 
 Mostly sunny, with a high near 88. Southwest wind around 5 mph.
Tonight
 
 Partly cloudy, with a low around 59. Southwest wind around 5 mph becoming calm.
Wednesday
 
 A slight chance of showers between noon and 1pm, then a chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 87. Calm wind becoming north around 5 mph in the afternoon. Chance of precipitation is 30%.
Wednesday Night
 
 A chance of thunderstorms before 7pm. Mostly clear, with a low around 52. Northeast wind around 10 mph. Chance of precipitation is 30%.
Thursday
 
 Sunny, with a high near 75. East wind around 10 mph.
Thursday Night
 
 Mostly clear, with a low around 48. East wind 5 to 10 mph becoming light and variable in the evening.
Friday
 
 Sunny, with a high near 82. Calm wind becoming northeast around 5 mph in the afternoon.
Friday Night
 
 Mostly clear, with a low around 53. East wind around 5 mph becoming calm.
Saturday
 
 Sunny, with a high near 78.
Saturday Night
 
 Mostly clear, with a low around 51.
Sunday
 
 Sunny, with a high near 78.
Sunday Night
 
 Mostly clear, with a low around 52.
Monday
 
 Sunny, with a high near 80.

 

Forecast from NOAA-NWS for Janesville WI.