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Glenn, IL Weather Forecast
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Glenn Weather Forecast
| THIS AFTERNOON | TONIGHT | FRIDAY | FRIDAY NIGHT | SATURDAY | SATURDAY NIGHT | SUNDAY | MONDAY | TUESDAY | TUESDAY NIGHT | WEDNESDAY |
 |  | | | | | | | | | |
| Mostly Sunny | Clear | Sunny | Mostly Clear | Sunny | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear |
| Hi: 99°FHi: 37°C | Lo: 75°FLo: 24°C | Hi: 99°FHi: 37°C | Lo: 75°FLo: 24°C | Hi: 99°FHi: 37°C | Hi: 95°FHi: 35°C Lo: 70°FLo: 21°C | Hi: 95°FHi: 35°C Lo: 70°FLo: 21°C | Hi: 95°FHi: 35°C Lo: 70°FLo: 21°C | Hi: 95°FHi: 35°C Lo: 70°FLo: 21°C | Hi: 99°FHi: 37°C Lo: 75°FLo: 24°C | Hi: 99°FHi: 37°C Lo: 75°FLo: 24°C |
POP = Probability of Precipitation.
Weather Outlook Updated: 237 PM CDT Thu Sep 03 2026 
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Issued: 239 PM CDT Thu Sep 3 2026
Key Messages
- An Extreme Heat Warning remains in effect through Saturday for a prolonged dangerous heatwave with daily heat index values ranging from 103-110 degrees. There is a 30-70% chance of needing to extend advisory level heat headlines into Sunday over southeast Missouri and adjacent portions of southern Illinois and west Kentucky.
- Multiple consecutive days of near record high temperatures in the upper 90s to 100 degrees and several record warm overnight low temperatures in the mid to upper...