Janesville, WI Weather & Growing Conditions
Tonight
62°F
Showers And Thunderstorms
Showers and thunderstorms. Some of the storms could produce heavy rain. Cloudy, with a low around 62. East wind 10 to 15 mph. Chance of precipitation is 90%. New rainfall amounts between 1 and 2 inches possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 62°F | Showers And Thunderstorms | 10 to 15 mph E | 91% |
| Saturday | 71°F | Showers And Thunderstorms | 10 to 15 mph SE | 98% |
| Saturday Night | 59°F | Showers And Thunderstorms | 5 to 10 mph NE | 80% |
| Sunday | 65°F | Chance Rain Showers | 15 mph NE | 42% |
| Sunday Night | 53°F | Slight Chance Rain Showers then Mostly Cloudy | 10 to 15 mph NE | 16% |
| Monday | 62°F | Chance Rain Showers | 15 mph NE | 32% |
| Monday Night | 48°F | Chance Rain Showers | 10 to 15 mph NE | 32% |
| Tuesday | 61°F | Slight Chance Rain Showers then Mostly Cloudy | 10 to 15 mph NE | 19% |
| Tuesday Night | 47°F | Mostly Cloudy | 5 to 10 mph NE | 8% |
| Wednesday | 64°F | Partly Sunny | 5 to 10 mph NE | 6% |
| Wednesday Night | 48°F | Partly Cloudy | 0 to 5 mph NE | 2% |
| Thursday | 66°F | Partly Sunny | 5 mph NE | 6% |
| Thursday Night | 50°F | Partly Cloudy | 0 to 5 mph NE | 5% |
| Friday | 68°F | Mostly Sunny | 0 to 5 mph NE | 5% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Janesville, WI
Last spring frost
Apr 26
First fall frost
Oct 15
Growing season
170 days
Hardiness zone
5b
Explore more for Janesville, WI: full frost dates · planting calendar · Wisconsin frost dates
Climate data from the nearest NOAA station, Afton - Janesville Wwtp, Wi (7.1 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.