Monmouth, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Monmouth, a city in Warren County, Illinois.
Today
87°F
Mostly Sunny
Mostly sunny, with a high near 87. Southwest wind 5 to 10 mph.
7-day forecast for Monmouth
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 87°F | Mostly Sunny | 5 to 10 mph SW | 1% |
| Tonight | 68°F | Chance Showers And Thunderstorms | 5 mph SE | 35% |
| Wednesday | 81°F | Showers And Thunderstorms Likely | 5 mph SW | 64% |
| Wednesday Night | 63°F | Showers And Thunderstorms | 0 to 5 mph N | 87% |
| Thursday | 80°F | Showers And Thunderstorms Likely then Slight Chance Showers And Thunderstorms | 5 mph NE | 63% |
| Thursday Night | 62°F | Partly Cloudy | 0 mph | 13% |
| Friday | 82°F | Mostly Sunny | 0 mph | 10% |
| Friday Night | 65°F | Mostly Clear | 0 to 5 mph SE | 12% |
| Saturday | 85°F | Sunny | 5 mph S | 10% |
| Saturday Night | 70°F | Mostly Clear | 5 to 10 mph S | 9% |
| Sunday | 87°F | Sunny | 10 mph SW | 9% |
| Sunday Night | 70°F | Partly Cloudy then Chance Showers And Thunderstorms | 5 to 10 mph S | 26% |
| Monday | 87°F | Chance Showers And Thunderstorms | 5 to 10 mph S | 26% |
| Monday Night | 71°F | Slight Chance Showers And Thunderstorms | 10 mph S | 29% |
Forecast source: National Weather Service (api.weather.gov) for Monmouth (40.914, -90.643). Updated through the day.
Growing snapshot for Monmouth
Last spring frost
Apr 22
First fall frost
Oct 15
Growing season
174 days
Hardiness zone
5b
More local growing data for Monmouth: nearby ZIP 61462 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Monmouth, Il (2.5 mi from Monmouth). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.