Colchester, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Colchester, a city in Mcdonough County, Illinois.
Today
87°F
Mostly Sunny
Mostly sunny, with a high near 87. South wind around 5 mph.
7-day forecast for Colchester
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 87°F | Mostly Sunny | 5 mph S | 0% |
| Tonight | 68°F | Mostly Cloudy then Slight Chance Showers And Thunderstorms | 0 to 5 mph SE | 20% |
| Wednesday | 83°F | Chance Showers And Thunderstorms | 0 to 5 mph S | 55% |
| Wednesday Night | 65°F | Showers And Thunderstorms | 0 to 5 mph N | 88% |
| Thursday | 81°F | Showers And Thunderstorms | 0 to 5 mph SE | 80% |
| Thursday Night | 63°F | Partly Cloudy | 0 mph | 12% |
| Friday | 83°F | Mostly Sunny | 0 mph | 6% |
| Friday Night | 65°F | Slight Chance Showers And Thunderstorms | 0 mph | 22% |
| Saturday | 86°F | Slight Chance Showers And Thunderstorms then Sunny | 0 to 5 mph S | 19% |
| Saturday Night | 70°F | Mostly Clear | 0 to 5 mph S | 8% |
| Sunday | 88°F | Sunny | 5 to 10 mph SW | 7% |
| Sunday Night | 70°F | Mostly Clear then Slight Chance Showers And Thunderstorms | 5 to 10 mph S | 16% |
| Monday | 88°F | Slight Chance Showers And Thunderstorms then Mostly Sunny | 5 to 10 mph SW | 16% |
| Monday Night | 71°F | Slight Chance Showers And Thunderstorms | 5 mph S | 27% |
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 Aug 4, 2026.