Colchester, IL Weather & Growing Conditions
Tonight
70°F
Partly Cloudy then Slight Chance Showers And Thunderstorms
A slight chance of showers and thunderstorms after 5am. Partly cloudy. Low around 70, with temperatures rising to around 72 overnight. Southeast wind 5 to 10 mph. Chance of precipitation is 20%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 70°F | Partly Cloudy then Slight Chance Showers And Thunderstorms | 5 to 10 mph SE | 17% |
| Saturday | 88°F | Mostly Cloudy | 5 to 10 mph S | 14% |
| Saturday Night | 67°F | Mostly Cloudy then Chance Showers And Thunderstorms | 0 to 5 mph NW | 62% |
| Sunday | 77°F | Rain Showers Likely | 0 to 15 mph N | 64% |
| Sunday Night | 59°F | Showers And Thunderstorms Likely | 10 to 15 mph NE | 66% |
| Monday | 66°F | Showers And Thunderstorms Likely | 10 to 15 mph NE | 66% |
| Monday Night | 54°F | Chance Rain Showers | 10 to 15 mph NE | 50% |
| Tuesday | 64°F | Chance Rain Showers then Mostly Cloudy | 10 mph NE | 32% |
| Tuesday Night | 49°F | Mostly Cloudy | 5 to 10 mph NE | 5% |
| Wednesday | 67°F | Mostly Sunny | 5 mph NE | 2% |
| Wednesday Night | 53°F | Partly Cloudy | 0 to 5 mph NE | 1% |
| Thursday | 69°F | Mostly Sunny | 0 to 5 mph NE | 4% |
| Thursday Night | 55°F | Partly Cloudy | 0 to 5 mph NE | 4% |
| Friday | 71°F | Mostly Sunny | 0 to 5 mph NE | 6% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Colchester, IL
Last spring frost
Apr 21
First fall frost
Oct 19
Growing season
180 days
Hardiness zone
6a
Explore more for Colchester, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, La Harpe, Il (13.8 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.