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St. Clair Park, IL Weather Forecast
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St. Clair Park Weather Forecast
| REST OF TODAY | TONIGHT | SUNDAY | SUNDAY NIGHT | MONDAY | MONDAY NIGHT | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT |
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| Chance of T-Storm | Partly Cloudy | Mostly Sunny | Chance of T-Storm | Mostly Sunny | Partly Cloudy | Sunny | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Chance of Showers | Chance of T-Storm |
| Hi: 95°FHi: 35°C | Lo: 79°FLo: 26°C | Hi: 95°FHi: 35°C | Lo: 71°FLo: 22°C | Hi: 85°FHi: 29°C | Lo: 69°FLo: 21°C | Hi: 89°FHi: 32°C | Lo: 71°FLo: 22°C | Hi: 91°FHi: 33°C | Lo: 69°FLo: 21°C | Hi: 81°FHi: 27°C | Lo: 65°FLo: 18°C |
| POP: 50% | POP: 40% | POP: 20% | POP: 20% | POP: 20% | POP: 20% | POP: 20% |
POP = Probability of Precipitation.
Weather Outlook Updated: 957 AM CDT Sat Aug 15 2026 
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St. Clair Park Forecast Discussion
Issued: 527 AM CDT Sat Aug 15 2026
Key Messages
- Localized flash flooding remains a threat through mid-morning across northeast MO and west-central Illinois, due to ongoing thunderstorms producing heavy rain rates (1-2+ inches per hour). Another round of locally heavy rain is possible (40-60%) in these same areas overnight tonight, although confidence is relatively low.
- Dangerous heat is expected again today and tomorrow, particularly along and south of I-70. More widespread heat relief is expected Mon...