Janesville, WI Weather & Growing Conditions
Overnight
56°F
Chance Light Rain
A chance of rain. Cloudy, with a low around 56. South wind around 15 mph. Chance of precipitation is 30%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 56°F | Chance Light Rain | 15 mph S | 29% |
| Wednesday | 60°F | Chance Light Rain | 15 mph SW | 25% |
| Wednesday Night | 45°F | Cloudy | 15 mph SW | 14% |
| Thursday | 55°F | Chance Light Rain | 10 to 15 mph W | 53% |
| Thursday Night | 37°F | Chance Light Rain then Mostly Cloudy | 10 to 15 mph N | 27% |
| Friday | 47°F | Partly Sunny | 10 to 15 mph N | 4% |
| Friday Night | 29°F | Partly Cloudy | 0 to 5 mph N | 0% |
| Saturday | 50°F | Sunny | 0 to 5 mph NW | 0% |
| Saturday Night | 31°F | Mostly Clear | 0 to 5 mph W | 1% |
| Sunday | 55°F | Sunny | 5 to 10 mph W | 5% |
| Sunday Night | 32°F | Mostly Clear | 0 to 5 mph W | 0% |
| Monday | 60°F | Sunny | 0 to 10 mph SW | 0% |
| Monday Night | 37°F | Mostly Clear | 5 to 10 mph W | 0% |
| Tuesday | 60°F | Sunny | 5 mph NW | 0% |
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
Explore more for Janesville, WI: full frost dates · planting calendar · Wisconsin frost dates
Climate data from the nearest NOAA station, Afton - Janesville Wwtp, Wi (2.4 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.