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City of Lanark, ILLanark, IL Weather Forecast
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Lanark Weather Forecast
| REST OF TODAY | TONIGHT | SATURDAY | SATURDAY NIGHT | SUNDAY | SUNDAY NIGHT | MONDAY | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY |
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| Chance of T-Storm | Chance of T-Storm | Patchy Fog | Partly Cloudy | Mostly Sunny | Partly Cloudy | Partly Cloudy | Partly Sunny | Chance of Showers | Partly Sunny | Chance of Showers | Partly Sunny |
| Hi: 95°FHi: 35°C | Lo: 71°FLo: 22°C | Hi: 89°FHi: 32°C | Lo: 65°FLo: 18°C | Hi: 81°FHi: 27°C | Hi: 81°FHi: 27°C Lo: 61°FLo: 16°C | Hi: 81°FHi: 27°C Lo: 61°FLo: 16°C | Hi: 89°FHi: 32°C | Lo: 71°FLo: 22°C | Hi: 89°FHi: 32°C | Lo: 69°FLo: 21°C | Hi: 81°FHi: 27°C |
| POP: 20% | POP: 20% | POP: 50% | POP: 40% |
POP = Probability of Precipitation.
Weather Outlook Updated: 916 AM CDT Fri Sep 04 2026 
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Issued: 616 AM CDT Fri Sep 4 2026
Key Messages
- Impactful heat will continue across the area through Saturday with peak heat indices of 100 to 110. The heat warnings may need to be expanded Saturday into the I-80 corridor east of the Quad Cities.
- There will be brief reprieves from the heat late this weekend and late next week. Another surge of heat and humidity with heat indices around 100 is expected the middle of next week. The overall pattern has a 55-70% probability of above normal temperatures through mid- September.
- There is...