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

Dangerous Heat and Heavy Rainfall into the Weekend

Hot temperatures and high humidity are forecast to continue across the mid-Mississippi Valley into this weekend. Heat Advisories remain in effect. Heavy to excessive rainfall occurring at times through the weekend could bring areas of flooding to parts of the northern Rockies, upper Midwest, central Great Lakes, and southern New England. Read More >

Current conditions at

St. Louis Regional Airport (KALN)

Lat: 38.89°NLon: 90.03°WElev: 518ft.

Fair

81°F

27°C

Humidity 74%
Wind Speed E 8 mph
Barometer 30.04 in
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Heat Index85°F (29°C)
Last update 18 Sep 9:50 pm CDT
Extended Forecast for

Carlinville IL

  • Tonight

    Tonight: Partly cloudy, with a low around 69. Southeast wind 6 to 8 mph.

    Low: 69 °F

    Partly Cloudy

  • Saturday

    Saturday: Increasing clouds, with a high near 96. South wind 5 to 7 mph becoming west in the morning.

    High: 96 °F

    Increasing
    Clouds

  • Saturday Night

    Saturday Night: Mostly cloudy, then gradually becoming mostly clear, with a low around 69. Light south wind.

    Low: 69 °F

    Decreasing
    Clouds

  • Sunday

    Sunday: A chance of showers, with thunderstorms also possible after 4pm. Partly sunny, with a high near 90. Calm wind becoming northwest around 6 mph in the afternoon. Chance of precipitation is 40%.

    High: 90 °F

    Chance
    Showers then
    Chance
    T-storms

  • Sunday Night

    Sunday Night: A chance of showers and thunderstorms before 1am, then showers likely and possibly a thunderstorm between 1am and 4am, then showers likely after 4am. Mostly cloudy, with a low around 61. Northeast wind 5 to 8 mph. Chance of precipitation is 60%.

    Low: 61 °F

    Chance
    T-storms then
    Showers
    Likely

  • Monday

    Monday: Showers likely before 7am, then showers likely and possibly a thunderstorm between 7am and 1pm, then a chance of showers and thunderstorms after 1pm. Mostly cloudy, with a high near 76. Chance of precipitation is 60%.

    High: 76 °F

    Showers
    Likely

  • Monday Night

    Monday Night: A 20 percent chance of showers. Mostly cloudy, with a low around 55.

    Low: 55 °F

    Slight Chance
    Showers

  • Tuesday

    Tuesday: Mostly cloudy, with a high near 70.

    High: 70 °F

    Mostly Cloudy

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 50.

    Low: 50 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Partly cloudy, with a low around 69. Southeast wind 6 to 8 mph.
Saturday
Increasing clouds, with a high near 96. South wind 5 to 7 mph becoming west in the morning.
Saturday Night
Mostly cloudy, then gradually becoming mostly clear, with a low around 69. Light south wind.
Sunday
A chance of showers, with thunderstorms also possible after 4pm. Partly sunny, with a high near 90. Calm wind becoming northwest around 6 mph in the afternoon. Chance of precipitation is 40%.
Sunday Night
A chance of showers and thunderstorms before 1am, then showers likely and possibly a thunderstorm between 1am and 4am, then showers likely after 4am. Mostly cloudy, with a low around 61. Northeast wind 5 to 8 mph. Chance of precipitation is 60%.
Monday
Showers likely before 7am, then showers likely and possibly a thunderstorm between 7am and 1pm, then a chance of showers and thunderstorms after 1pm. Mostly cloudy, with a high near 76. Chance of precipitation is 60%.
Monday Night
A 20 percent chance of showers. Mostly cloudy, with a low around 55.
Tuesday
Mostly cloudy, with a high near 70.
Tuesday Night
Mostly cloudy, with a low around 50.
Wednesday
Mostly sunny, with a high near 73.
Wednesday Night
Partly cloudy, with a low around 52.
Thursday
Mostly sunny, with a high near 75.
Thursday Night
Partly cloudy, with a low around 54.
Friday
Mostly sunny, with a high near 76.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Carlinville IL
 39.3°N 89.86°W (Elev. 627 ft)
Last Update:
9:26 pm CDT Sep 18, 2026
Forecast Valid:
10pm CDT Sep 18, 2026-6pm CDT Sep 25, 2026
 
Forecast Discussion
 
Get as KML Get as XML

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