Grand Detour, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Grand Detour, a community in Lee County, Illinois.
Overnight
60°F
Mostly Clear
Mostly clear. Low around 60, with temperatures rising to around 62 overnight. South wind around 0 mph.
7-day forecast for Grand Detour
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 60°F | Mostly Clear | 0 mph | 0% |
| Tuesday | 84°F | Mostly Sunny | 0 to 10 mph SSW | 5% |
| Tuesday Night | 66°F | Chance Showers And Thunderstorms | 0 to 5 mph SSW | 74% |
| Wednesday | 76°F | Showers And Thunderstorms Likely | 0 to 5 mph W | 74% |
| Wednesday Night | 60°F | Showers And Thunderstorms | 0 to 5 mph N | 79% |
| Thursday | 78°F | Chance Rain Showers | 0 mph | 42% |
| Thursday Night | 59°F | Mostly Clear | 0 mph | 14% |
| Friday | 81°F | Mostly Sunny | 0 mph | 11% |
| Friday Night | 62°F | Mostly Clear | 0 mph | 11% |
| Saturday | 84°F | Sunny | 0 to 5 mph SSW | 8% |
| Saturday Night | 68°F | Mostly Clear then Slight Chance Showers And Thunderstorms | 5 mph SSW | 19% |
| Sunday | 86°F | Slight Chance Showers And Thunderstorms then Mostly Sunny | 5 to 10 mph SSW | 19% |
| Sunday Night | 68°F | Chance Showers And Thunderstorms | 5 to 10 mph SSW | 38% |
| Monday | 85°F | Chance Showers And Thunderstorms | 5 to 10 mph SSW | 35% |
Forecast source: National Weather Service (api.weather.gov) for Grand Detour (41.901, -89.413). Updated through the day.
Growing snapshot for Grand Detour
Last spring frost
Apr 21
First fall frost
Oct 19
Growing season
180 days
Hardiness zone
5b
More local growing data for Grand Detour: nearby ZIP 61057 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Amboy
Ashton
Compton
Dixon
Franklin Grove
Harmon
Lee
Lee Center
Lost Nation
Nachusa
Nelson
Paw Paw
Steward
Sublette
West Brooklyn
Climate data from the nearest NOAA station, Dixon 1W, Il (6.7 mi from Grand Detour). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.