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

73°F

23°C

Humidity 87%
Wind Speed Calm
Barometer 29.98 in
Dewpoint 69°F (21°C)
Visibility 10.00 mi
Last update 19 Sep 2:55 am CDT
Extended Forecast for

Gillespie IL

  • Overnight

    Overnight: Mostly clear, with a low around 70. South wind around 7 mph.

    Low: 70 °F

    Mostly Clear

  • Saturday

    Saturday: Increasing clouds, with a high near 95. South wind 3 to 7 mph.

    High: 95 °F

    Increasing
    Clouds

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 69. Light south wind.

    Low: 69 °F

    Partly Cloudy

  • Sunday

    Sunday: A slight chance of showers before 9am, then a slight chance of showers and thunderstorms after 4pm. Partly sunny, with a high near 89. Calm wind becoming northwest around 6 mph in the afternoon. Chance of precipitation is 20%.

    High: 89 °F

    Slight Chance
    Showers then
    Slight Chance
    T-storms

  • Sunday Night

    Sunday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 62. Northeast wind 7 to 10 mph. Chance of precipitation is 70%.

    Low: 62 °F

    Chance
    T-storms then
    Showers
    Likely

  • Monday

    Monday: Showers likely and possibly a thunderstorm before 10am, then showers likely between 10am and 1pm, then a chance of showers and thunderstorms after 1pm. Mostly cloudy, with a high near 75. Chance of precipitation is 70%.

    High: 75 °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: A 20 percent chance of showers before 1pm. Partly sunny, with a high near 69.

    High: 69 °F

    Slight Chance
    Showers

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 51.

    Low: 51 °F

    Mostly Cloudy

Detailed Forecast

Overnight
Mostly clear, with a low around 70. South wind around 7 mph.
Saturday
Increasing clouds, with a high near 95. South wind 3 to 7 mph.
Saturday Night
Partly cloudy, with a low around 69. Light south wind.
Sunday
A slight chance of showers before 9am, then a slight chance of showers and thunderstorms after 4pm. Partly sunny, with a high near 89. Calm wind becoming northwest around 6 mph in the afternoon. Chance of precipitation is 20%.
Sunday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 62. Northeast wind 7 to 10 mph. Chance of precipitation is 70%.
Monday
Showers likely and possibly a thunderstorm before 10am, then showers likely between 10am and 1pm, then a chance of showers and thunderstorms after 1pm. Mostly cloudy, with a high near 75. Chance of precipitation is 70%.
Monday Night
A 20 percent chance of showers. Mostly cloudy, with a low around 55.
Tuesday
A 20 percent chance of showers before 1pm. Partly sunny, with a high near 69.
Tuesday Night
Mostly cloudy, with a low around 51.
Wednesday
Mostly sunny, with a high near 72.
Wednesday Night
Partly cloudy, with a low around 52.
Thursday
Mostly sunny, with a high near 74.
Thursday Night
Partly cloudy, with a low around 54.
Friday
Mostly sunny, with a high near 76.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Gillespie IL
 39.14°N 89.84°W (Elev. 659 ft)
Last Update:
1:26 am CDT Sep 19, 2026
Forecast Valid:
3am CDT Sep 19, 2026-6pm CDT Sep 25, 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