Harmon, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Harmon, a village in Lee County, Illinois.
This Afternoon
78°F
Showers And Thunderstorms
Showers and thunderstorms before 5pm, then a chance of showers and thunderstorms. Some of the storms could produce heavy rain. Cloudy, with a high near 78. South southeast wind 5 to 10 mph. Chance of precipitation is 90%. New rainfall amounts between 1 and 2 inches possible.
7-day forecast for Harmon
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 78°F | Showers And Thunderstorms | 5 to 10 mph SSE | 88% |
| Tonight | 63°F | Showers And Thunderstorms Likely then Showers And Thunderstorms | 5 to 10 mph ENE | 95% |
| Sunday | 70°F | Showers And Thunderstorms Likely | 10 to 15 mph NE | 58% |
| Sunday Night | 56°F | Chance Showers And Thunderstorms | 15 mph NE | 40% |
| Monday | 65°F | Chance Rain Showers | 15 mph ENE | 50% |
| Monday Night | 51°F | Chance Rain Showers | 10 to 15 mph NE | 29% |
| Tuesday | 64°F | Slight Chance Rain Showers then Partly Sunny | 10 to 15 mph NE | 19% |
| Tuesday Night | 48°F | Partly Cloudy | 5 to 15 mph NE | 10% |
| Wednesday | 67°F | Mostly Sunny | 5 to 10 mph NE | 2% |
| Wednesday Night | 50°F | Partly Cloudy | 5 to 10 mph NE | 1% |
| Thursday | 69°F | Mostly Sunny | 5 mph NNE | 4% |
| Thursday Night | 52°F | Partly Cloudy | 0 to 5 mph NE | 4% |
| Friday | 72°F | Mostly Sunny | 5 mph NE | 2% |
| Friday Night | 52°F | Partly Cloudy | 0 to 5 mph ENE | 2% |
Forecast source: National Weather Service (api.weather.gov) for Harmon (41.723, -89.554). Updated through the day.
Growing snapshot for Harmon
Last spring frost
Apr 24
First fall frost
Oct 14
Growing season
172 days
Hardiness zone
5b
More local growing data for Harmon: nearby ZIP 61042 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Amboy
Ashton
Compton
Dixon
Franklin Grove
Grand Detour
Lee
Lee Center
Lost Nation
Nachusa
Nelson
Paw Paw
Steward
Sublette
West Brooklyn
Climate data from the nearest NOAA station, Walnut, Il (9.5 mi from Harmon). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.