Harmon, IL Weather & Growing Conditions
Tonight
55°F
Rain
Rain. Cloudy. Low around 55, with temperatures rising to around 58 overnight. South wind 10 to 15 mph, with gusts as high as 25 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 55°F | Rain | 10 to 15 mph S | 82% |
| Wednesday | 58°F | Chance Rain then Mostly Cloudy | 15 mph SSW | 27% |
| Wednesday Night | 46°F | Mostly Cloudy then Slight Chance Rain Showers | 10 to 15 mph SW | 21% |
| Thursday | 55°F | Chance Rain Showers | 10 to 15 mph WSW | 49% |
| Thursday Night | 42°F | Chance Rain Showers | 5 to 10 mph NW | 31% |
| Friday | 51°F | Slight Chance Rain Showers then Partly Sunny | 5 to 10 mph N | 16% |
| Friday Night | 34°F | Partly Cloudy | 0 to 5 mph NNW | 1% |
| Saturday | 52°F | Mostly Sunny | 0 to 5 mph WNW | 3% |
| Saturday Night | 34°F | Partly Cloudy | 0 mph | 4% |
| Sunday | 58°F | Mostly Sunny | 5 mph W | 12% |
| Sunday Night | 35°F | Mostly Clear | 0 to 5 mph W | 4% |
| Monday | 62°F | Sunny | 5 to 10 mph SW | 2% |
| Monday Night | 39°F | Mostly Clear | 5 mph W | 0% |
| Tuesday | 62°F | Sunny | 5 mph WNW | 0% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Harmon, IL
Last spring frost
Apr 24
First fall frost
Oct 14
Growing season
172 days
Hardiness zone
5b
Explore more for Harmon, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Walnut, Il (9.5 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.