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

Chester County Airport (KMQS)

Lat: 39.98°NLon: 75.87°WElev: 659ft.

Fair

79°F

26°C

Humidity 67%
Wind Speed N 6 mph
Barometer 30.11 in
Dewpoint 67°F (19°C)
Visibility 10.00 mi
Heat Index81°F (27°C)
Last update 18 Sep 12:55 pm EDT
Extended Forecast for

Saint Peters PASimilar City Names

  • This Afternoon

    This Afternoon: Mostly sunny, with a high near 80. North wind around 10 mph.

    High: 80 °F

    Mostly Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 54. North wind around 5 mph.

    Low: 54 °F

    Partly Cloudy

  • Saturday

    Saturday: Partly sunny, with a high near 73. East wind 5 to 10 mph.

    High: 73 °F

    Partly Sunny

  • Saturday Night

    Saturday Night: A chance of showers after 2am. Mostly cloudy, with a low around 58. Southeast wind around 5 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 58 °F

    Mostly Cloudy
    then Chance
    Showers

  • Sunday

    Sunday: Showers, mainly after 8am. High near 72. South wind 5 to 10 mph. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.

    High: 72 °F

    Showers
    Likely then
    Showers

  • Sunday Night

    Sunday Night: Showers and possibly a thunderstorm before 2am, then a chance of showers. Low around 60. Chance of precipitation is 80%. New rainfall amounts between a half and three quarters of an inch possible.

    Low: 60 °F

    Showers

  • Monday

    Monday: A chance of showers. Mostly cloudy, with a high near 68. Chance of precipitation is 40%.

    High: 68 °F

    Chance
    Showers

  • Monday Night

    Monday Night: A chance of showers. Mostly cloudy, with a low around 54. Chance of precipitation is 50%.

    Low: 54 °F

    Chance
    Showers

  • Tuesday

    Tuesday: A chance of showers. Mostly cloudy, with a high near 61. Chance of precipitation is 50%.

    High: 61 °F

    Chance
    Showers

Detailed Forecast

This Afternoon
Mostly sunny, with a high near 80. North wind around 10 mph.
Tonight
Partly cloudy, with a low around 54. North wind around 5 mph.
Saturday
Partly sunny, with a high near 73. East wind 5 to 10 mph.
Saturday Night
A chance of showers after 2am. Mostly cloudy, with a low around 58. Southeast wind around 5 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.
Sunday
Showers, mainly after 8am. High near 72. South wind 5 to 10 mph. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.
Sunday Night
Showers and possibly a thunderstorm before 2am, then a chance of showers. Low around 60. Chance of precipitation is 80%. New rainfall amounts between a half and three quarters of an inch possible.
Monday
A chance of showers. Mostly cloudy, with a high near 68. Chance of precipitation is 40%.
Monday Night
A chance of showers. Mostly cloudy, with a low around 54. Chance of precipitation is 50%.
Tuesday
A chance of showers. Mostly cloudy, with a high near 61. Chance of precipitation is 50%.
Tuesday Night
A chance of showers. Mostly cloudy, with a low around 50. Chance of precipitation is 40%.
Wednesday
A chance of showers. Mostly cloudy, with a high near 61. Chance of precipitation is 40%.
Wednesday Night
A chance of showers. Mostly cloudy, with a low around 50. Chance of precipitation is 40%.
Thursday
A chance of showers. Partly sunny, with a high near 64. Chance of precipitation is 40%.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Saint Peters PASimilar City Names
 40.14°N 75.79°W (Elev. 600 ft)
Last Update:
4:09 am EDT Sep 18, 2026
Forecast Valid:
1pm EDT Sep 18, 2026-6pm EDT Sep 24, 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