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.

Fair

77°F

25°C

Humidity 90%
Wind Speed SW 9 mph
Barometer 29.85 in (1010.0 mb)
Dewpoint 74°F (23°C)
Visibility 10.00 mi
Heat Index78°F (26°C)
Last update 12 Aug 4:54 am CDT
Extended Forecast for

Assumption IL

Heat Advisory August 12, 12:00pm until August 12, 08:00pm
Click here for hazard details and duration
Heat Advisory

  • Today

    Today: A slight chance of showers between 11am and 1pm, then a chance of showers and thunderstorms after 1pm. Increasing clouds, with a high near 89. Heat index values as high as 102. South southwest wind 6 to 9 mph becoming north in the afternoon. Winds could gust as high as 18 mph. Chance of precipitation is 40%.

    High: 89 °F

    Slight Chance
    Showers then
    Chance
    T-storms

  • Tonight

    Tonight: A 30 percent chance of showers and thunderstorms, mainly after 2am. Mostly cloudy, with a low around 70. East southeast wind 5 to 7 mph.

    Low: 70 °F

    Chance
    T-storms

  • Thursday

    Thursday: A 30 percent chance of showers and thunderstorms, mainly before 9am. Mostly cloudy, with a high near 87. South southeast wind around 7 mph.

    High: 87 °F

    Chance
    T-storms then
    Mostly Cloudy

  • Thursday Night

    Thursday Night: A chance of showers and thunderstorms. Partly cloudy, with a low around 72. South wind 5 to 7 mph becoming east after midnight. Chance of precipitation is 50%.

    Low: 72 °F

    Chance
    T-storms

  • Friday

    Friday: Partly sunny, with a high near 91. East wind around 6 mph.

    High: 91 °F

    Partly Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 73. East wind 6 to 8 mph.

    Low: 73 °F

    Partly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 94. South southwest wind around 7 mph.

    High: 94 °F

    Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 74.

    Low: 74 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 92.

    High: 92 °F

    Sunny

Detailed Forecast

Today
A slight chance of showers between 11am and 1pm, then a chance of showers and thunderstorms after 1pm. Increasing clouds, with a high near 89. Heat index values as high as 102. South southwest wind 6 to 9 mph becoming north in the afternoon. Winds could gust as high as 18 mph. Chance of precipitation is 40%.
Tonight
A 30 percent chance of showers and thunderstorms, mainly after 2am. Mostly cloudy, with a low around 70. East southeast wind 5 to 7 mph.
Thursday
A 30 percent chance of showers and thunderstorms, mainly before 9am. Mostly cloudy, with a high near 87. South southeast wind around 7 mph.
Thursday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 72. South wind 5 to 7 mph becoming east after midnight. Chance of precipitation is 50%.
Friday
Partly sunny, with a high near 91. East wind around 6 mph.
Friday Night
Partly cloudy, with a low around 73. East wind 6 to 8 mph.
Saturday
Sunny, with a high near 94. South southwest wind around 7 mph.
Saturday Night
Mostly clear, with a low around 74.
Sunday
Sunny, with a high near 92.
Sunday Night
A 30 percent chance of showers after 1am. Partly cloudy, with a low around 69.
Monday
Mostly sunny, with a high near 84.
Monday Night
Partly cloudy, with a low around 64.
Tuesday
Sunny, with a high near 84.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Assumption IL
 39.51°N 89.05°W (Elev. 636 ft)
Last Update:
3:56 am CDT Aug 12, 2026
Forecast Valid:
5am CDT Aug 12, 2026-6pm CDT Aug 18, 2026
 
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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