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City of Mattoon, IllinoisMattoon, IL Weather Forecast
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Mattoon Weather Forecast
| TONIGHT | SUNDAY | SUNDAY NIGHT | LABOR DAY | MONDAY NIGHT | TUESDAY | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY | FRIDAY NIGHT |
 |  |  | | | | |  |  | |  | |
| Partly Cloudy | Sunny | Mostly Clear | Sunny | Mostly Clear | Mostly Clear | Mostly Clear | Chance of T-Storm | Chance of Showers | Partly Cloudy | Partly Cloudy | Mostly Clear |
| Lo: 65°FLo: 18°C | Hi: 85°FHi: 29°C | Lo: 59°FLo: 15°C | Hi: 85°FHi: 29°C | Lo: 61°FLo: 16°C | Hi: 95°FHi: 35°C Lo: 71°FLo: 22°C | Hi: 95°FHi: 35°C Lo: 71°FLo: 22°C | Lo: 69°FLo: 21°C | Hi: 85°FHi: 29°C | Hi: 85°FHi: 29°C Lo: 59°FLo: 15°C | Hi: 85°FHi: 29°C Lo: 59°FLo: 15°C | Hi: 90°FHi: 32°C Lo: 61°FLo: 16°C |
| POP: 40% | POP: 40% |
POP = Probability of Precipitation.
Weather Outlook Updated: 737 PM CDT Sat Sep 05 2026 
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Instant definitions for any meteorological term.
Instant definitions for any meteorological term.
Issued: 602 PM CDT Sat Sep 5 2026
Key Messages
- Dangerous heat continues across central Illinois through early evening, with peak heat index values ranging from 100 to 110F.
- A cold front brings welcomed relief Sunday and Monday, pushing high temperatures into the 80s for most locations and dropping heat indices into the 80s and 90s.
- High heat and humidity return Tuesday and Wednesday, bringing another risk for triple-digit heat index values.
Discussion
... Issued at 113 PM CDT Sat Sep 5 2026
A backdoor cold front continues its slow s...