Posen, IL Weather & Growing Conditions
Tonight
61°F
Rain Likely
Rain likely. Cloudy. Low around 61, with temperatures rising to around 63 overnight. South wind around 15 mph, with gusts as high as 30 mph. Chance of precipitation is 70%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 61°F | Rain Likely | 15 mph S | 74% |
| Wednesday | 65°F | Chance Rain then Mostly Cloudy | 15 mph SSW | 68% |
| Wednesday Night | 49°F | Mostly Cloudy | 15 mph SW | 12% |
| Thursday | 58°F | Mostly Cloudy then Slight Chance Rain Showers | 10 to 15 mph WSW | 22% |
| Thursday Night | 44°F | Chance Rain Showers | 5 to 10 mph WNW | 47% |
| Friday | 54°F | Chance Rain Showers | 10 mph N | 37% |
| Friday Night | 39°F | Slight Chance Rain then Mostly Cloudy | 5 to 10 mph NNW | 18% |
| Saturday | 52°F | Mostly Sunny | 5 mph WNW | 12% |
| Saturday Night | 37°F | Partly Cloudy | 0 to 5 mph WSW | 6% |
| Sunday | 57°F | Mostly Sunny | 5 to 10 mph W | 14% |
| Sunday Night | 38°F | Mostly Clear | 5 mph WNW | 11% |
| Monday | 60°F | Sunny | 5 to 10 mph WSW | 7% |
| Monday Night | 42°F | Mostly Clear | 5 to 10 mph WSW | 2% |
| Tuesday | 62°F | Mostly Sunny | 5 mph W | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Posen, IL
Last spring frost
Apr 10
First fall frost
Nov 1
Growing season
203 days
Hardiness zone
6a
Explore more for Posen, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Chicago Midway Ap 3Sw, Il (8.8 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.