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Sullivan Lake Weather Forecast
| REST OF TONIGHT | MONDAY | MONDAY NIGHT | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY | FRIDAY NIGHT | SATURDAY |
 |  |  | |  |  |  |  |  | | | |
| Partly Cloudy | Clearing | Patchy Fog | Patchy Fog | Mostly Cloudy | Chance of Showers | Chance of T-Storm | Chance of T-Storm | Chance of Showers | Partly Cloudy | Partly Cloudy | Partly Cloudy |
| Lo: 49°FLo: 9°C | Hi: 71°FHi: 22°C | Lo: 51°FLo: 11°C | Hi: 75°FHi: 24°C | Lo: 60°FLo: 16°C | Hi: 75°FHi: 24°C | Lo: 65°FLo: 18°C | Hi: 71°FHi: 22°C | Lo: 55°FLo: 13°C | Hi: 65°FHi: 18°C | Lo: 51°FLo: 11°C | Hi: 65°FHi: 18°C |
| POP: 40% | POP: 60% | POP: 80% | POP: 40% |
POP = Probability of Precipitation.
Weather Outlook Updated: 146 AM CDT Mon Sep 28 2026 
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Issued: 337 AM CDT Mon Sep 28 2026
Key Messages
- Fog, including areas of dense fog, will persist through mid- morning across portions of northern Illinois and northwestern Indiana. The greatest coverage of dense fog is expected to remain near/south of I-80 and near/east of I-55.
- Widespread rain is likely across the region in the late Wednesday through Thursday time frame.
Discussion
... Issued at 337 AM CDT Mon Sep 28 2026
Calm winds and mostly clear skies have allowed for fog to develop in portions of northern Illinois and northwest ...