Weather World
McArthur Lake, IL Weather Forecast
Quick Weather Clicks
Settings
Sun & Moon
McArthur Lake Weather Forecast
| REST OF TONIGHT | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY | FRIDAY NIGHT | SATURDAY | SATURDAY NIGHT | SUNDAY |
 |  | | | | | |  | |  |  | |
| Clear | Sunny | Clear | Sunny | Clear | Sunny | Mostly Clear | Chance of Showers | Mostly Clear | Partly Cloudy | Partly Cloudy | Mostly Sunny |
| Lo: 75°FLo: 24°C | Hi: 100°FHi: 38°C | Lo: 79°FLo: 26°C | Hi: 100°FHi: 38°C | Lo: 79°FLo: 26°C | Hi: 100°FHi: 38°C | Lo: 79°FLo: 26°C | Hi: 99°FHi: 37°C | Lo: 75°FLo: 24°C | Hi: 95°FHi: 35°C Lo: 70°FLo: 21°C | Hi: 95°FHi: 35°C Lo: 70°FLo: 21°C | Hi: 90°FHi: 32°C |
| POP: 30% |
POP = Probability of Precipitation.
Weather Outlook Updated: 937 PM CDT Mon Aug 31 2026 
McArthur Lake Radar Loop
Use the map search tool if you want to place a location marker on the radar map...
McArthur Lake Weather Map
McArthur Lake Quick Facts
McArthur Lake Forecast Discussion
Meteorlogic Glosserator
Instant definitions for any meteorological term.
Instant definitions for any meteorological term.
Issued: 605 PM CDT Mon Aug 31 2026
Key Messages
- Heat index values between 100 and 105+ degrees are expected Tuesday through Thursday. There is a high chance (>60%) of heat index values exceeding 100 degrees south of a line from Beardstown to Terre Haute on Tuesday, expanding to areas south of Interstate 74 on Wednesday.
- More seasonal conditions arrive by late weekend, lowering high temperatures into the mid-80s behind a slow moving cold front. The passing cold front brings a low (20%) chance of showers and thunderstorms Friday and...