Waterloo, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Waterloo, a city in Monroe County, Illinois.
This Afternoon
72°F
Rain
Rain and a slight chance of thunderstorms. Cloudy. High near 72, with temperatures falling to around 67 in the afternoon. South wind 16 to 20 mph, with gusts as high as 33 mph. Chance of precipitation is 100%.
7-day forecast for Waterloo
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 72°F | Rain | 16 to 20 mph S | 97% |
| Tonight | 53°F | Rain | 7 to 15 mph SW | 94% |
| Wednesday | 63°F | Mostly Cloudy | 6 to 12 mph W | 4% |
| Wednesday Night | 46°F | Partly Cloudy | 5 mph SW | 0% |
| Thursday | 69°F | Sunny | 5 to 8 mph SW | 2% |
| Thursday Night | 47°F | Slight Chance Light Rain then Mostly Cloudy | 5 mph W | 24% |
| Friday | 60°F | Partly Sunny | 5 to 9 mph NW | 3% |
| Friday Night | 44°F | Partly Cloudy | 5 mph NW | 1% |
| Saturday | 58°F | Partly Sunny | 3 mph N | 0% |
| Saturday Night | 40°F | Partly Cloudy | 2 mph NW | 1% |
| Sunday | 59°F | Sunny | 2 to 7 mph W | 6% |
| Sunday Night | 39°F | Mostly Clear | 5 mph W | 6% |
| Monday | 62°F | Sunny | 5 mph SW | 3% |
| Monday Night | 40°F | Mostly Clear | 2 mph SW | 3% |
Forecast source: National Weather Service (api.weather.gov) for Waterloo (38.341, -90.153). Updated through the day.
Growing snapshot for Waterloo
Last spring frost
Apr 9
First fall frost
Oct 26
Growing season
197 days
Hardiness zone
7a
More local growing data for Waterloo: nearby ZIP 62298 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Festus, Mo (14.5 mi from Waterloo). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 3, 2026.