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Roundhouse Lake, IL Weather Forecast
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Roundhouse Lake Weather Forecast
| TONIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY | FRIDAY NIGHT | SATURDAY | SUNDAY | MONDAY | TUESDAY |
 |  |  |  |  | | | |  | | |
| Chance of Showers | Chance of T-Storm | Chance of T-Storm | Sunny | Mostly Clear | Chance of T-Storm | Mostly Clear | Mostly Clear | Partly Cloudy | Partly Cloudy | Partly Cloudy |
| Lo: 65°FLo: 18°C | Hi: 80°FHi: 27°C | Lo: 61°FLo: 16°C | Hi: 80°FHi: 27°C | Lo: 61°FLo: 16°C | Hi: 81°FHi: 27°C | Hi: 80°FHi: 27°C Lo: 61°FLo: 16°C | Hi: 80°FHi: 27°C Lo: 61°FLo: 16°C | Hi: 79°FHi: 26°C Lo: 61°FLo: 16°C | Hi: 79°FHi: 26°C Lo: 61°FLo: 16°C | Hi: 79°FHi: 26°C Lo: 61°FLo: 16°C |
| POP: 20% | POP: 30% | POP: 20% | POP: 30% |
POP = Probability of Precipitation.
Weather Outlook Updated: 637 PM CDT Tue Aug 18 2026 
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Roundhouse Lake Forecast Discussion
Issued: 616 PM CDT Tue Aug 18 2026
Key Messages
- While heavier rain with an overnight thunderstorm complex stays to our south, periods of showers and a few thunderstorms are expected late tonight into Wednesday morning.
- A persistent northwest flow will keep temperatures and humidity levels in check the next several days, with highs in the upper 70s to lower 80s common.
Discussion
... Issued at 125 PM CDT Tue Aug 18 2026
A general northwest upper flow will prevail over the next several days, as a large low...