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Optimist Park, IL Weather Forecast
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Optimist Park Weather Forecast
| TODAY | TONIGHT | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY | SATURDAY | SUNDAY |
 |  | |  |  |  |  |  |  | | |
| Chance of Showers | Chance of Showers | Chance of Showers | Mostly Clear | Sunny | Partly Cloudy | Partly Cloudy | Mostly Cloudy | Mostly Cloudy | Mostly Cloudy | Mostly Cloudy |
| Hi: 61°FHi: 16°C | Lo: 55°FLo: 13°C | Hi: 65°FHi: 18°C | Lo: 49°FLo: 9°C | Hi: 69°FHi: 21°C | Hi: 69°FHi: 21°C Lo: 51°FLo: 11°C | Hi: 69°FHi: 21°C Lo: 51°FLo: 11°C | Hi: 71°FHi: 22°C Lo: 55°FLo: 13°C | Hi: 71°FHi: 22°C Lo: 55°FLo: 13°C | Hi: 71°FHi: 22°C Lo: 55°FLo: 13°C | Hi: 71°FHi: 22°C Lo: 55°FLo: 13°C |
| POP: 50% | POP: 50% | POP: 40% |
POP = Probability of Precipitation.
Weather Outlook Updated: 241 AM CDT Mon Sep 21 2026 
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Issued: 234 AM CDT Mon Sep 21 2026
Key Messages
- An upper low over the northern plains will roll toward the area through Tuesday morning, leading to occasional showers and continued cool and cloudy conditions early to mid week. Then a precip break for Wednesday thru Friday.
- Expectations for a few nice dry early Fall days are growing for mid to late week, with highs in the 60s/near 70 and lows in the 40s/50s.
Aviation
/06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1238 AM CDT Mon Sep 21 2026
High pressure acrs the northwestern GRT LKS and...