Waterloo, IL Weather & Growing Conditions
Tonight
54°F
Chance Light Rain
A chance of rain before 2am, then a slight chance of drizzle between 2am and 5am. Mostly cloudy, with a low around 54. Southwest wind around 9 mph, with gusts as high as 21 mph. Chance of precipitation is 40%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 54°F | Chance Light Rain | 9 mph SW | 37% |
| Wednesday | 62°F | Mostly Cloudy | 6 to 13 mph W | 4% |
| Wednesday Night | 44°F | Mostly Clear | 5 mph W | 0% |
| Thursday | 64°F | Sunny | 5 to 8 mph W | 1% |
| Thursday Night | 45°F | Mostly Cloudy | 6 mph NW | 9% |
| Friday | 57°F | Partly Sunny | 6 to 9 mph NW | 4% |
| Friday Night | 40°F | Partly Cloudy | 5 mph N | 1% |
| Saturday | 55°F | Partly Sunny | 3 mph NW | 0% |
| Saturday Night | 37°F | Partly Cloudy | 2 mph W | 1% |
| Sunday | 61°F | Sunny | 2 to 6 mph W | 7% |
| Sunday Night | 37°F | Mostly Clear | 3 mph W | 6% |
| Monday | 65°F | Sunny | 6 mph SW | 2% |
| Monday Night | 41°F | Mostly Clear | 5 mph SW | 0% |
| Tuesday | 68°F | Sunny | 5 mph W | 0% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Waterloo, IL
Last spring frost
Apr 9
First fall frost
Oct 26
Growing season
197 days
Hardiness zone
7a
Explore more for Waterloo, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Festus, Mo (14.5 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.