Waterloo, IL Weather & Growing Conditions
Overnight
54°F
Mostly Cloudy
Mostly cloudy, with a low around 54. West wind around 7 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 54°F | Mostly Cloudy | 7 mph W | 7% |
| Wednesday | 61°F | Slight Chance Drizzle then Mostly Cloudy | 6 to 12 mph W | 12% |
| Wednesday Night | 44°F | Mostly Clear | 5 mph W | 0% |
| Thursday | 64°F | Sunny | 5 to 8 mph W | 0% |
| Thursday Night | 46°F | Mostly Cloudy | 6 mph NW | 2% |
| Friday | 56°F | Partly Sunny | 6 to 9 mph N | 1% |
| Friday Night | 37°F | Partly Cloudy | 2 to 6 mph N | 0% |
| Saturday | 54°F | Mostly Sunny | 3 mph N | 0% |
| Saturday Night | 35°F | Partly Cloudy | 2 mph NW | 0% |
| Sunday | 59°F | Sunny | 5 mph NW | 1% |
| Sunday Night | 36°F | Clear | 2 mph W | 0% |
| Monday | 64°F | Sunny | 3 mph SW | 0% |
| Monday Night | 41°F | Clear | 3 mph SW | 1% |
| Tuesday | 68°F | Sunny | 3 mph W | 1% |
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.