Weather World
City of Waterloo, IllinoisWaterloo, IL Weather Forecast
Quick Weather Clicks
Settings
Sun & Moon
Waterloo Weather Forecast
| TONIGHT | SATURDAY | SATURDAY NIGHT | SUNDAY | SUNDAY NIGHT | LABOR DAY | MONDAY NIGHT | TUESDAY | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | FRIDAY |
 |  | |  | | | | | |  |  | |
| Mostly Clear | Thunderstorms | Mostly Clear | Sunny | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm |
| Lo: 75°FLo: 24°C | Hi: 99°FHi: 37°C | Lo: 71°FLo: 22°C | Hi: 95°FHi: 35°C | Lo: 65°FLo: 18°C | Hi: 91°FHi: 33°C Lo: 65°FLo: 18°C | Hi: 91°FHi: 33°C Lo: 65°FLo: 18°C | Hi: 99°FHi: 37°C Lo: 71°FLo: 22°C | Hi: 99°FHi: 37°C Lo: 71°FLo: 22°C | Lo: 71°FLo: 22°C | Hi: 91°FHi: 33°C Lo: 65°FLo: 18°C | Hi: 91°FHi: 33°C Lo: 65°FLo: 18°C |
| POP: 20% | POP: 20% | POP: 20% | POP: 20% |
POP = Probability of Precipitation.
Weather Outlook Updated: 253 PM CDT Fri Sep 04 2026 
Waterloo Radar Loop
Use the map search tool if you want to place a location marker on the radar map...
Waterloo Weather Map
Waterloo Quick Facts
Waterloo Forecast Discussion
Meteorlogic Glosserator
Instant definitions for any meteorological term.
Instant definitions for any meteorological term.
Issued: 251 PM CDT Fri Sep 4 2026
Key Messages
- Late summer heat will continue on Saturday before temperatures cool on Sunday and Labor Day. The relative humidity will also be much lower on Labor Day compared to earlier in the holiday weekend.
- Another period of heat and near-record breaking temperatures is forecast Tuesday into Wednesday.
Aviation
/18Z TAFS THROUGH 00Z SUNDAY/... Issued at 1219 PM CDT Fri Sep 4 2026
Dry/VFR conditions with diurnal cumulus dissipating this evening along with winds becoming light/variable are expected.