Janesville, IA Weather & Growing Conditions
Today
52°F
Chance Rain Showers
A chance of rain showers. Cloudy. High near 52, with temperatures falling to around 50 in the afternoon. West southwest wind 12 to 18 mph, with gusts as high as 24 mph. Chance of precipitation is 40%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 52°F | Chance Rain Showers | 12 to 18 mph WSW | 38% |
| Tonight | 44°F | Chance Rain Showers | 13 to 16 mph W | 53% |
| Thursday | 52°F | Chance Rain Showers | 15 mph NW | 42% |
| Thursday Night | 37°F | Mostly Cloudy | 8 to 13 mph N | 11% |
| Friday | 47°F | Mostly Sunny | 5 to 9 mph N | 3% |
| Friday Night | 28°F | Partly Cloudy | 0 to 3 mph N | 0% |
| Saturday | 50°F | Mostly Sunny | 0 to 6 mph W | 0% |
| Saturday Night | 34°F | Mostly Clear | 5 mph W | 2% |
| Sunday | 56°F | Sunny | 5 to 8 mph W | 3% |
| Sunday Night | 36°F | Clear | 5 mph SW | 0% |
| Monday | 62°F | Sunny | 3 to 12 mph SW | 0% |
| Monday Night | 39°F | Mostly Clear | 3 to 7 mph W | 0% |
| Tuesday | 60°F | Sunny | 5 mph NW | 0% |
| Tuesday Night | 40°F | Partly Cloudy | 3 mph NNE | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Janesville, IA
Last spring frost
Apr 27
First fall frost
Oct 10
Growing season
165 days
Hardiness zone
5a
Explore more for Janesville, IA: full frost dates · planting calendar · Iowa frost dates
Climate data from the nearest NOAA station, Waterloo Muni Ap, Ia (8.3 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.