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Lancaster, IL Weather Forecast
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Lancaster Weather Forecast
| OVERNIGHT | FRIDAY | FRIDAY NIGHT | SATURDAY | SATURDAY NIGHT | SUNDAY | MONDAY | TUESDAY | TUESDAY NIGHT | WEDNESDAY | THURSDAY |
 |  | | | | | | | | |  |
| Clear | Sunny | Mostly Clear | Sunny | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear | Chance of Showers |
| Lo: 75°FLo: 24°C | Hi: 99°FHi: 37°C | Lo: 75°FLo: 24°C | Hi: 99°FHi: 37°C | Lo: 71°FLo: 22°C | Hi: 91°FHi: 33°C Lo: 65°FLo: 18°C | Hi: 91°FHi: 33°C Lo: 65°FLo: 18°C | Hi: 91°FHi: 33°C Lo: 65°FLo: 18°C | Hi: 99°FHi: 37°C Lo: 75°FLo: 24°C | Hi: 99°FHi: 37°C Lo: 75°FLo: 24°C | Hi: 95°FHi: 35°C |
| POP: 30% |
POP = Probability of Precipitation.
Weather Outlook Updated: 127 AM CDT Fri Sep 04 2026 
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Issued: 255 AM CDT Fri Sep 4 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 30-90% chance of triple digit heat index values continuing into Sunday over southeast Missouri, the Purchase Area of Kentucky, and adjacent portions of southern Illinois.
- Near record high temperatures in the upper 90s to around 100 degrees and near record warm overnight low temperatures in the mid to upper 70s are expected...