Waterloo, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Waterloo, a city in Monroe County, Illinois.
Overnight
64°F
Clear
Clear, with a low around 64. Southeast wind around 1 mph.
7-day forecast for Waterloo
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 64°F | Clear | 1 mph SE | 0% |
| Tuesday | 86°F | Sunny | 2 mph SE | 0% |
| Tuesday Night | 66°F | Mostly Clear | 3 mph SE | 0% |
| Wednesday | 89°F | Sunny | 5 mph S | 5% |
| Wednesday Night | 70°F | Slight Chance Showers And Thunderstorms | 6 mph S | 55% |
| Thursday | 86°F | Showers And Thunderstorms Likely | 5 mph S | 66% |
| Thursday Night | 69°F | Chance Showers And Thunderstorms | 3 mph S | 47% |
| Friday | 86°F | Chance Showers And Thunderstorms | 3 mph SW | 47% |
| Friday Night | 69°F | Chance Showers And Thunderstorms | 2 mph SW | 38% |
| Saturday | 88°F | Chance Showers And Thunderstorms | 3 mph S | 38% |
| Saturday Night | 70°F | Mostly Clear | 5 mph S | 9% |
| Sunday | 90°F | Sunny | 6 mph S | 8% |
| Sunday Night | 72°F | Mostly Clear | 7 mph S | 5% |
| Monday | 92°F | Sunny | 7 mph SW | 5% |
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 Aug 4, 2026.