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

San Marcos, San Marcos Municipal Airport (KHYI)

Lat: 29.89°NLon: 97.86°WElev: 597ft.

Fair

75°F

24°C

Humidity 76%
Wind Speed Calm
Barometer 30.06 in (1017.1 mb)
Dewpoint 67°F (19°C)
Visibility 10.00 mi
Last update 31 Jul 7:56 am CDT
Extended Forecast for

San Marcos TX

  • Today

    Today: Sunny and hot, with a high near 99. Heat index values as high as 102. West southwest wind around 5 mph becoming calm in the afternoon.

    High: 99 °F

    Hot

  • Tonight

    Tonight: Partly cloudy, with a low around 76. South southeast wind around 5 mph.

    Low: 76 °F

    Partly Cloudy

  • Friday

    Friday: A slight chance of showers between 1pm and 4pm, then a slight chance of showers and thunderstorms after 4pm. Mostly sunny and hot, with a high near 99. Heat index values as high as 103. Calm wind becoming southeast around 5 mph. Chance of precipitation is 20%.

    High: 99 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Friday Night

    Friday Night: A slight chance of showers and thunderstorms before 10pm, then a slight chance of showers between 10pm and 1am. Partly cloudy, with a low around 76. Southeast wind around 5 mph becoming calm after midnight. Chance of precipitation is 20%.

    Low: 76 °F

    Slight Chance
    T-storms then
    Slight Chance
    Showers

  • Saturday

    Saturday: A chance of showers between 1pm and 4pm, then a chance of showers and thunderstorms after 4pm. Sunny, with a high near 97. Calm wind becoming southeast around 5 mph. Chance of precipitation is 30%.

    High: 97 °F

    Sunny then
    Chance
    T-storms

  • Saturday Night

    Saturday Night: A chance of showers and thunderstorms before 10pm, then a slight chance of showers between 10pm and 1am. Partly cloudy, with a low around 76. East wind around 5 mph becoming calm in the evening. Chance of precipitation is 30%.

    Low: 76 °F

    Chance
    T-storms then
    Slight Chance
    Showers

  • Sunday

    Sunday: Sunny, with a high near 97. Calm wind becoming south around 5 mph.

    High: 97 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 77. South wind around 5 mph.

    Low: 77 °F

    Mostly Clear

  • Monday

    Monday: Mostly sunny, with a high near 94. South wind around 5 mph becoming east southeast in the afternoon.

    High: 94 °F

    Mostly Sunny

Detailed Forecast

Today
Sunny and hot, with a high near 99. Heat index values as high as 102. West southwest wind around 5 mph becoming calm in the afternoon.
Tonight
Partly cloudy, with a low around 76. South southeast wind around 5 mph.
Friday
A slight chance of showers between 1pm and 4pm, then a slight chance of showers and thunderstorms after 4pm. Mostly sunny and hot, with a high near 99. Heat index values as high as 103. Calm wind becoming southeast around 5 mph. Chance of precipitation is 20%.
Friday Night
A slight chance of showers and thunderstorms before 10pm, then a slight chance of showers between 10pm and 1am. Partly cloudy, with a low around 76. Southeast wind around 5 mph becoming calm after midnight. Chance of precipitation is 20%.
Saturday
A chance of showers between 1pm and 4pm, then a chance of showers and thunderstorms after 4pm. Sunny, with a high near 97. Calm wind becoming southeast around 5 mph. Chance of precipitation is 30%.
Saturday Night
A chance of showers and thunderstorms before 10pm, then a slight chance of showers between 10pm and 1am. Partly cloudy, with a low around 76. East wind around 5 mph becoming calm in the evening. Chance of precipitation is 30%.
Sunday
Sunny, with a high near 97. Calm wind becoming south around 5 mph.
Sunday Night
Mostly clear, with a low around 77. South wind around 5 mph.
Monday
Mostly sunny, with a high near 94. South wind around 5 mph becoming east southeast in the afternoon.
Monday Night
Partly cloudy, with a low around 75.
Tuesday
Sunny, with a high near 95.
Tuesday Night
Mostly clear, with a low around 75.
Wednesday
Sunny, with a high near 96.
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ABOUT THIS FORECAST

 
Point Forecast:
San Marcos TX
 29.88°N 97.94°W (Elev. 577 ft)
Last Update:
7:44 am CDT Jul 31, 2025
Forecast Valid:
8am CDT Jul 31, 2025-6pm CDT Aug 6, 2025
 
Forecast Discussion
 
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Additional Resources

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High Temperature

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Chance of Precipitation