Monmouth, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Monmouth, a city in Warren County, Illinois.
Tonight
69°F
Mostly Cloudy then Chance Showers And Thunderstorms
A chance of showers and thunderstorms after 3am. Mostly cloudy, with a low around 69. Southeast wind around 10 mph, with gusts as high as 20 mph. Chance of precipitation is 30%.
7-day forecast for Monmouth
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 69°F | Mostly Cloudy then Chance Showers And Thunderstorms | 10 mph SE | 31% |
| Saturday | 85°F | Chance Showers And Thunderstorms | 5 to 10 mph S | 40% |
| Saturday Night | 66°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 mph N | 72% |
| Sunday | 74°F | Showers And Thunderstorms Likely | 5 to 10 mph NE | 72% |
| Sunday Night | 58°F | Showers And Thunderstorms Likely | 10 to 15 mph NE | 69% |
| Monday | 65°F | Showers And Thunderstorms Likely | 15 mph NE | 67% |
| Monday Night | 53°F | Chance Rain Showers | 10 to 15 mph NE | 49% |
| Tuesday | 63°F | Chance Rain Showers | 10 to 15 mph NE | 30% |
| Tuesday Night | 49°F | Partly Cloudy | 5 to 10 mph NE | 6% |
| Wednesday | 67°F | Mostly Sunny | 5 to 10 mph NE | 2% |
| Wednesday Night | 52°F | Partly Cloudy | 0 to 5 mph NE | 1% |
| Thursday | 69°F | Partly Sunny | 5 mph NE | 5% |
| Thursday Night | 54°F | Partly Cloudy | 0 to 5 mph NE | 5% |
| Friday | 71°F | Mostly Sunny | 0 to 5 mph NE | 5% |
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 Sep 19, 2026.