Monmouth, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Monmouth, a city in Warren County, Illinois.
Tonight
52°F
Mostly Cloudy
Mostly cloudy. Low around 52, with temperatures rising to around 54 overnight. Southwest wind 10 to 15 mph, with gusts as high as 25 mph.
7-day forecast for Monmouth
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 52°F | Mostly Cloudy | 10 to 15 mph SW | 10% |
| Wednesday | 56°F | Slight Chance Rain Showers | 15 mph SW | 18% |
| Wednesday Night | 45°F | Mostly Cloudy | 10 to 15 mph SW | 8% |
| Thursday | 55°F | Chance Rain Showers | 10 to 15 mph W | 28% |
| Thursday Night | 42°F | Slight Chance Rain Showers then Mostly Cloudy | 5 to 10 mph NW | 22% |
| Friday | 50°F | Partly Sunny | 5 to 10 mph N | 6% |
| Friday Night | 32°F | Mostly Clear | 0 to 5 mph N | 0% |
| Saturday | 51°F | Sunny | 0 to 5 mph NW | 0% |
| Saturday Night | 34°F | Mostly Clear | 0 to 5 mph W | 1% |
| Sunday | 57°F | Sunny | 5 mph W | 1% |
| Sunday Night | 36°F | Clear | 0 to 5 mph W | 1% |
| Monday | 63°F | Sunny | 0 to 10 mph SW | 0% |
| Monday Night | 41°F | Mostly Clear | 5 mph W | 0% |
| Tuesday | 64°F | Sunny | 5 mph NW | 0% |
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 Nov 4, 2026.