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Lake Jacksonville Weather Forecast
| TODAY | TONIGHT | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | FRIDAY | FRIDAY NIGHT | SATURDAY | SUNDAY |
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| Sunny | Mostly Clear | Sunny | Clear | Sunny | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear | Mostly Clear |
| Hi: 95°FHi: 35°C | Lo: 75°FLo: 24°C | Hi: 99°FHi: 37°C | Lo: 79°FLo: 26°C | Hi: 99°FHi: 37°C | Hi: 95°FHi: 35°C Lo: 75°FLo: 24°C | Hi: 95°FHi: 35°C Lo: 75°FLo: 24°C | Hi: 95°FHi: 35°C Lo: 75°FLo: 24°C | Hi: 90°FHi: 32°C Lo: 70°FLo: 21°C | Hi: 90°FHi: 32°C Lo: 70°FLo: 21°C | Hi: 90°FHi: 32°C Lo: 70°FLo: 21°C |
POP = Probability of Precipitation.
Weather Outlook Updated: 637 AM CDT Mon Aug 31 2026 
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Issued: 627 AM CDT Mon Aug 31 2026
Key Messages
- Hot and mostly dry weather is forecast through mid week, with afternoon heat indices peaking above 100 degrees in west- central Illinois today and areawide Tuesday through Thursday.
- A Heat Advisory is posted from this afternoon through Thursday afternoon southwest of Marshall, Woodford, McLean, Champaign and Edgar counties.
Discussion
... Issued at 345 AM CDT Mon Aug 31 2026
Main weather story this week will be the late season heat wave, with afternoon heat indices reaching the upper 90...