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

78°F

26°C

Humidity 85%
Wind Speed NW 5 mph
Barometer 30.05 in (1016.9 mb)
Dewpoint 73°F (23°C)
Visibility 10.00 mi
Heat Index80°F (27°C)
Last update 28 Aug 7:56 am CDT
Extended Forecast for

San Marcos TX

  • Today

    Today: A 30 percent chance of showers and thunderstorms, mainly after 4pm. Sunny, with a high near 97. Heat index values as high as 105. Calm wind becoming east southeast around 5 mph in the afternoon.

    High: 97 °F

    Mostly Sunny
    then Chance
    Showers

  • Tonight

    Tonight: A 30 percent chance of showers, mainly before 7pm. Mostly clear, with a low around 75. East southeast wind around 5 mph becoming calm in the evening.

    Low: 75 °F

    Chance
    Showers then
    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 97. Heat index values as high as 102. Calm wind becoming southeast around 5 mph in the afternoon.

    High: 97 °F

    Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 75. East southeast wind around 5 mph becoming south southwest after midnight.

    Low: 75 °F

    Mostly Clear

  • Sunday

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

    High: 97 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 75. Southeast wind 5 to 10 mph.

    Low: 75 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 97. Calm wind becoming south around 5 mph in the morning.

    High: 97 °F

    Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 75. Southeast wind 5 to 10 mph, with gusts as high as 20 mph.

    Low: 75 °F

    Mostly Clear

  • Tuesday

    Tuesday: Mostly sunny, with a high near 97. Calm wind becoming south around 5 mph in the morning.

    High: 97 °F

    Mostly Sunny

Detailed Forecast

Today
A 30 percent chance of showers and thunderstorms, mainly after 4pm. Sunny, with a high near 97. Heat index values as high as 105. Calm wind becoming east southeast around 5 mph in the afternoon.
Tonight
A 30 percent chance of showers, mainly before 7pm. Mostly clear, with a low around 75. East southeast wind around 5 mph becoming calm in the evening.
Saturday
Sunny, with a high near 97. Heat index values as high as 102. Calm wind becoming southeast around 5 mph in the afternoon.
Saturday Night
Mostly clear, with a low around 75. East southeast wind around 5 mph becoming south southwest after midnight.
Sunday
Sunny, with a high near 97. Calm wind becoming south southeast around 5 mph in the afternoon.
Sunday Night
Mostly clear, with a low around 75. Southeast wind 5 to 10 mph.
Monday
Sunny, with a high near 97. Calm wind becoming south around 5 mph in the morning.
Monday Night
Mostly clear, with a low around 75. Southeast wind 5 to 10 mph, with gusts as high as 20 mph.
Tuesday
Mostly sunny, with a high near 97. Calm wind becoming south around 5 mph in the morning.
Tuesday Night
Mostly clear, with a low around 75.
Wednesday
Sunny, with a high near 98.
Wednesday Night
Mostly clear, with a low around 75.
Thursday
Mostly sunny, with a high near 98.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
San Marcos TX
 29.88°N 97.94°W (Elev. 577 ft)
Last Update:
7:56 am CDT Aug 28, 2026
Forecast Valid:
8am CDT Aug 28, 2026-6pm CDT Sep 3, 2026
 
Forecast Discussion
 
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Additional Resources

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation