Colchester, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Colchester, a city in Mcdonough County, Illinois.
Tonight
69°F
Partly Cloudy then Slight Chance Showers And Thunderstorms
A slight chance of showers and thunderstorms after 5am. Partly cloudy. Low around 69, with temperatures rising to around 71 overnight. Southeast wind 5 to 10 mph. Chance of precipitation is 20%.
7-day forecast for Colchester
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 69°F | Partly Cloudy then Slight Chance Showers And Thunderstorms | 5 to 10 mph SE | 17% |
| Saturday | 88°F | Mostly Cloudy | 5 mph S | 14% |
| Saturday Night | 67°F | Mostly Cloudy then Chance Showers And Thunderstorms | 0 to 5 mph NW | 61% |
| 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 | 52°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) for Colchester (40.426, -90.792). Updated through the day.
Growing snapshot for Colchester
Last spring frost
Apr 21
First fall frost
Oct 19
Growing season
180 days
Hardiness zone
6a
More local growing data for Colchester: nearby ZIP 62326 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Adair
Bardolph
Blandinsville
Bushnell
Georgetown
Good Hope
Industry
Macomb
Prairie City
Sciota
Tennessee
Climate data from the nearest NOAA station, La Harpe, Il (13.8 mi from Colchester). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.