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City Reservoir, IL Weather Forecast
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City Reservoir Weather Forecast
| TONIGHT | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY | FRIDAY NIGHT | SATURDAY | SATURDAY NIGHT | SUNDAY |
 |  | | | | | |  | | |  |  |
| Mostly Clear | Sunny | Clear | Sunny | Clear | Sunny | Mostly Clear | Chance of T-Storm | Mostly Clear | Mostly Clear | Partly Cloudy | Partly Cloudy |
| Lo: 75°FLo: 24°C | Hi: 100°FHi: 38°C | Lo: 75°FLo: 24°C | Hi: 100°FHi: 38°C | Lo: 75°FLo: 24°C | Hi: 100°FHi: 38°C | Lo: 75°FLo: 24°C | Hi: 99°FHi: 37°C | Hi: 95°FHi: 35°C Lo: 75°FLo: 24°C | Hi: 95°FHi: 35°C Lo: 75°FLo: 24°C | Hi: 91°FHi: 33°C Lo: 70°FLo: 21°C | Hi: 91°FHi: 33°C Lo: 70°FLo: 21°C |
| POP: 30% |
POP = Probability of Precipitation.
Weather Outlook Updated: 547 PM CDT Mon Aug 31 2026 
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Issued: 553 PM CDT Mon Aug 31 2026
Key Messages
- A prolonged duration Heat Advisory remains in effect thru Friday for daily heat indices 100-110 degrees.
- A small chance of showers and thunderstorms Friday and Saturday will help transition toward an end to the prolonged duration heat.
Discussion
... Issued at 1212 PM CDT Mon Aug 31 2026
Strong high pressure at the surface and aloft remains locked in here this week, pumping up the heat and humidity in the process. Our prolonged duration Heat Advisory running the course of the week looks...