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.

Overcast

81°F

27°C

Humidity 85%
Wind Speed S 8 mph
Barometer 29.98 in (1014.1 mb)
Dewpoint 76°F (24°C)
Visibility 10.00 mi
Heat Index87°F (31°C)
Last update 4 Aug 8:56 am CDT
Extended Forecast for

San Marcos TX

  • Today

    Today: Sunny and hot, with a high near 99. Heat index values as high as 104. South wind 5 to 10 mph.

    High: 99 °F

    Hot

  • Tonight

    Tonight: Mostly clear, with a low around 76. South southeast wind 5 to 10 mph, with gusts as high as 20 mph.

    Low: 76 °F

    Mostly Clear

  • Wednesday

    Wednesday: Mostly sunny, with a high near 98. Heat index values as high as 104. South wind 5 to 10 mph.

    High: 98 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Increasing clouds, with a low around 76. South southeast wind 5 to 10 mph, with gusts as high as 20 mph.

    Low: 76 °F

    Increasing
    Clouds

  • Thursday

    Thursday: Mostly sunny, with a high near 98. South wind around 5 mph.

    High: 98 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 76. Southeast wind 5 to 10 mph.

    Low: 76 °F

    Partly Cloudy

  • Friday

    Friday: Mostly sunny, with a high near 96. Calm wind becoming south around 5 mph in the morning.

    High: 96 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 75. Southeast wind around 5 mph.

    Low: 75 °F

    Partly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 95. Calm wind becoming southeast around 5 mph in the afternoon.

    High: 95 °F

    Mostly Sunny

Detailed Forecast

Today
Sunny and hot, with a high near 99. Heat index values as high as 104. South wind 5 to 10 mph.
Tonight
Mostly clear, with a low around 76. South southeast wind 5 to 10 mph, with gusts as high as 20 mph.
Wednesday
Mostly sunny, with a high near 98. Heat index values as high as 104. South wind 5 to 10 mph.
Wednesday Night
Increasing clouds, with a low around 76. South southeast wind 5 to 10 mph, with gusts as high as 20 mph.
Thursday
Mostly sunny, with a high near 98. South wind around 5 mph.
Thursday Night
Partly cloudy, with a low around 76. Southeast wind 5 to 10 mph.
Friday
Mostly sunny, with a high near 96. Calm wind becoming south around 5 mph in the morning.
Friday Night
Partly cloudy, with a low around 75. Southeast wind around 5 mph.
Saturday
Mostly sunny, with a high near 95. Calm wind becoming southeast around 5 mph in the afternoon.
Saturday Night
Mostly clear, with a low around 75.
Sunday
Mostly sunny, with a high near 95.
Sunday Night
Mostly clear, with a low around 75.
Monday
Mostly sunny, with a high near 96.
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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:
6:42 am CDT Aug 4, 2026
Forecast Valid:
9am CDT Aug 4, 2026-6pm CDT Aug 10, 2026
 
Forecast Discussion
 
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Additional Resources

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Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation