National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Hazardous Weather Conditions

Current conditions at

Decatur Airport (KDEC)

Lat: 39.83°NLon: 88.87°WElev: 670ft.

Mostly Cloudy

75°F

24°C

Humidity 90%
Wind Speed S 7 mph
Barometer 29.96 in (1013.9 mb)
Dewpoint 72°F (22°C)
Visibility 8.00 mi
Last update 8 Jun 7:54 am CDT
Extended Forecast for

Illiopolis IL

Flood Watch until June 9, 01:00am
Click here for hazard details and duration
Flood Watch
  •  
    Flood Watch until June 9, 01:00am

    NOW until 1:00am Tue

    Flood Watch

  • Today

    High: 83 °F

    Showers then
    T-storms

  • Tonight

    Tonight: Showers likely and possibly a thunderstorm before 8pm, then a chance of showers and thunderstorms after 8pm. Mostly cloudy, with a low around 70. South wind 6 to 10 mph, with gusts as high as 17 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 70 °F

    Showers
    Likely then
    Chance
    T-storms

  • Tuesday

    Tuesday: A 20 percent chance of showers before 8am. Partly sunny, with a high near 89. West southwest wind 7 to 11 mph, with gusts as high as 16 mph.

    High: 89 °F

    Slight Chance
    Showers then
    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 72. South southwest wind 7 to 9 mph, with gusts as high as 16 mph.

    Low: 72 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny, with a high near 92. South southwest wind 10 to 18 mph, with gusts as high as 26 mph.

    High: 92 °F

    Sunny

  • Wednesday Night

    Wednesday Night: A chance of showers and thunderstorms, then showers likely after 1am. Partly cloudy, with a low around 72. South wind 13 to 18 mph, with gusts as high as 26 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 72 °F

    Chance
    T-storms then
    Showers
    Likely

  • Thursday

    Thursday: A chance of showers, then showers and thunderstorms likely after 1pm. Mostly sunny, with a high near 90. Breezy, with a south southwest wind 13 to 20 mph, with gusts as high as 26 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 90 °F

    Chance
    Showers then
    T-storms
    Likely and
    Breezy

  • Thursday Night

    Thursday Night: Showers likely and possibly a thunderstorm before 1am. Mostly cloudy, with a low around 67. Chance of precipitation is 60%.

    Low: 67 °F

    Showers
    Likely

Detailed Forecast

Today
Showers and possibly a thunderstorm, mainly before 4pm, then showers and thunderstorms likely after 4pm. High near 83. South southeast wind 11 to 14 mph, with gusts as high as 22 mph. Chance of precipitation is 80%. New rainfall amounts between a half and three quarters of an inch possible.
Tonight
Showers likely and possibly a thunderstorm before 8pm, then a chance of showers and thunderstorms after 8pm. Mostly cloudy, with a low around 70. South wind 6 to 10 mph, with gusts as high as 17 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Tuesday
A 20 percent chance of showers before 8am. Partly sunny, with a high near 89. West southwest wind 7 to 11 mph, with gusts as high as 16 mph.
Tuesday Night
Mostly clear, with a low around 72. South southwest wind 7 to 9 mph, with gusts as high as 16 mph.
Wednesday
Sunny, with a high near 92. South southwest wind 10 to 18 mph, with gusts as high as 26 mph.
Wednesday Night
A chance of showers and thunderstorms, then showers likely after 1am. Partly cloudy, with a low around 72. South wind 13 to 18 mph, with gusts as high as 26 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Thursday
A chance of showers, then showers and thunderstorms likely after 1pm. Mostly sunny, with a high near 90. Breezy, with a south southwest wind 13 to 20 mph, with gusts as high as 26 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Thursday Night
Showers likely and possibly a thunderstorm before 1am. Mostly cloudy, with a low around 67. Chance of precipitation is 60%.
Friday
Sunny, with a high near 87.
Friday Night
A 30 percent chance of showers after 1am. Mostly clear, with a low around 65.
Saturday
A chance of showers. Mostly sunny, with a high near 87.
Saturday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 66.
Sunday
A chance of showers and thunderstorms. Partly sunny, with a high near 82.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Illiopolis IL
 39.85°N 89.26°W (Elev. 607 ft)
Last Update:
8:47 am CDT Jun 8, 2026
Forecast Valid:
8am CDT Jun 8, 2026-6pm CDT Jun 14, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation