Weather WorldBig Flat Lake, IL Weather Forecast
Quick Weather Clicks
Settings
Sun & Moon
Big Flat Lake Weather Forecast
| THIS AFTERNOON | TONIGHT | SUNDAY | SUNDAY NIGHT | MONDAY | MONDAY NIGHT | TUESDAY | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY |
 |  |  |  | |  | | | | | | |
| Sunny | Partly Cloudy | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Mostly Clear | Mostly Clear | Mostly Clear | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm |
| Hi: 90°FHi: 32°C | Lo: 69°FLo: 21°C | Hi: 89°FHi: 32°C | Lo: 61°FLo: 16°C | Hi: 89°FHi: 32°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 | Lo: 71°FLo: 22°C | Hi: 90°FHi: 32°C Lo: 65°FLo: 18°C | Hi: 90°FHi: 32°C Lo: 65°FLo: 18°C | Hi: 85°FHi: 29°C |
| POP: 20% | POP: 20% | POP: 20% | POP: 20% | POP: 30% | POP: 30% | POP: 20% |
POP = Probability of Precipitation.
Weather Outlook Updated: 1103 AM CDT Sat Sep 12 2026 
Big Flat Lake Radar Loop
Use the map search tool if you want to place a location marker on the radar map...
Big Flat Lake Weather Map
Big Flat Lake Quick Facts
Big Flat Lake Forecast Discussion
Meteorlogic Glosserator
Instant definitions for any meteorological term.
Instant definitions for any meteorological term.
Issued: 618 AM CDT Sat Sep 12 2026
Key Messages
- There is a chance (20-30%) for showers and thunderstorms across central and northeast Missouri into west central Illinois late this afternoon and tonight. The chance for rain spreads southeast across the area on Sunday.
- Temperatures will remain above normal for most of the area into next week with a chance for rain continuing, mainly across northern Missouri into central Illinois.
Aviation
/00Z TAFS THROUGH 06Z SUNDAY/... Issued at 1037 PM CDT Fri Sep 11 2026
Fog will be found initially...