Illiopolis, IL Weather Forecast
Local 7-day forecast
Chance Showers And Thunderstorms
Track current conditions, temperature changes, wind, and the full daily outlook for Illiopolis, IL in one place.
A chance of showers and thunderstorms before 1pm, then showers and thunderstorms. Mostly sunny, with a high near 87. West southwest wind 3 to 8 mph. Chance of precipitation is 80%. New rainfall amounts between a quarter and half of an inch possible.
Local Weather Overview
This forecast page for Illiopolis, IL is designed for quick trip planning, giving you a clean read on daytime highs, overnight lows, and changing conditions across the upcoming forecast window. Latest sync: Jul 15, 2026 7:21 AM CDT.
The active forecast window currently covers Jul 17 to Jul 21, 2026 for Illiopolis, IL.
Page Snapshot
- Page focus
- city weather
- Forecast window
- Jul 17 to Jul 21, 2026
- Latest sync
- Jul 15, 2026 7:21 AM CDT
- Forecast office
- ILX
- Source
- NOAA / NWS
Daily Outlook
This Week in Illiopolis
Saturday looks like the warmest upcoming period in Illiopolis at 90 degrees F.
Sunday Night is the coolest period ahead with temperatures near 70 degrees F.
The strongest winds are forecast for Tuesday at about 8 to 15 mph NNW.
Precipitation is mentioned in 6 upcoming forecast periods.
Forecast Details
- Last updated
- Jul 15, 2026 7:21 AM CDT
- Coverage
- 5 days
- Time zone
- America/Chicago
- Forecast office
- ILX
- Radar station
- KILX
Weather data is provided by the National Weather Service and refreshed automatically for U.S. locations.
Open NOAA sourceExtended Forecast
Showers and thunderstorms before 7pm, then a slight chance of showers and thunderstorms between 7pm and 1am. Partly cloudy, with a low around 72. West southwest wind around 7 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch possible.
A slight chance of showers and thunderstorms after 1pm. Sunny, with a high near 90.
A slight chance of showers and thunderstorms before 1am. Mostly clear, with a low around 71.
Sunny, with a high near 88.
Mostly clear, with a low around 70.
A slight chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 90.
A slight chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 71.
Sunny, with a high near 86.
Detailed Forecast
| Period | Conditions | Temp | Wind |
|---|---|---|---|
|
Friday
Jul 17
|
Chance Showers And Thunderstorms
|
87°F |
3 to 8 mph
WSW
|
|
Friday Night
Jul 17
|
Showers And Thunderstorms then Slight Chance Showers And Thunderstorms
|
72°F |
7 mph
WSW
|
|
Saturday
Jul 18
|
Sunny then Slight Chance Showers And Thunderstorms
|
90°F |
7 to 13 mph
WSW
|
|
Saturday Night
Jul 18
|
Slight Chance Showers And Thunderstorms
|
71°F |
7 to 10 mph
W
|
|
Sunday
Jul 19
|
Sunny
|
88°F |
8 mph
NW
|
|
Sunday Night
Jul 19
|
Mostly Clear
|
70°F |
7 mph
S
|
|
Monday
Jul 20
|
Mostly Sunny then Slight Chance Showers And Thunderstorms
|
90°F |
8 to 12 mph
SW
|
|
Monday Night
Jul 20
|
Slight Chance Showers And Thunderstorms
|
71°F |
10 mph
WNW
|
|
Tuesday
Jul 21
|
Sunny
|
86°F |
8 to 15 mph
NNW
|
Nearby Forecasts
Explore weather pages for nearby cities and major places around Illiopolis.