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.

A Few Clouds

93°F

34°C

Humidity 50%
Wind Speed SE 7 mph
Barometer 30.06 in (1016.9 mb)
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Heat Index101°F (38°C)
Last update 9 Aug 12:56 pm CDT
Extended Forecast for

San Marcos TX

  • This Afternoon

    This Afternoon: A 20 percent chance of showers and thunderstorms after 4pm. Mostly sunny, with a high near 96. Heat index values as high as 104. South southeast wind around 5 mph.

    High: 96 °F

    Slight Chance
    T-storms

  • Tonight

    Tonight: Increasing clouds, with a low around 76. Southeast wind 5 to 10 mph.

    Low: 76 °F

    Increasing
    Clouds

  • Monday

    Monday: Mostly sunny, with a high near 96. Heat index values as high as 105. Light south wind becoming south southeast 5 to 10 mph in the morning.

    High: 96 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 76. South southeast wind 5 to 10 mph.

    Low: 76 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Sunny, with a high near 98. South wind 5 to 10 mph.

    High: 98 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 76. South southeast wind 5 to 10 mph.

    Low: 76 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny and hot, with a high near 99. South wind 5 to 10 mph.

    High: 99 °F

    Hot

  • Wednesday Night

    Wednesday Night: Clear, with a low around 76. South southeast wind 10 to 15 mph, with gusts as high as 20 mph.

    Low: 76 °F

    Clear

  • Thursday

    Thursday: Mostly sunny and hot, with a high near 99. South wind 10 to 15 mph.

    High: 99 °F

    Hot

Detailed Forecast

This Afternoon
A 20 percent chance of showers and thunderstorms after 4pm. Mostly sunny, with a high near 96. Heat index values as high as 104. South southeast wind around 5 mph.
Tonight
Increasing clouds, with a low around 76. Southeast wind 5 to 10 mph.
Monday
Mostly sunny, with a high near 96. Heat index values as high as 105. Light south wind becoming south southeast 5 to 10 mph in the morning.
Monday Night
Partly cloudy, with a low around 76. South southeast wind 5 to 10 mph.
Tuesday
Sunny, with a high near 98. South wind 5 to 10 mph.
Tuesday Night
Mostly clear, with a low around 76. South southeast wind 5 to 10 mph.
Wednesday
Sunny and hot, with a high near 99. South wind 5 to 10 mph.
Wednesday Night
Clear, with a low around 76. South southeast wind 10 to 15 mph, with gusts as high as 20 mph.
Thursday
Mostly sunny and hot, with a high near 99. South wind 10 to 15 mph.
Thursday Night
Mostly clear, with a low around 76.
Friday
Mostly sunny and hot, with a high near 99.
Friday Night
Mostly clear, with a low around 76.
Saturday
Mostly sunny, with a high near 97.
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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:
12:46 pm CDT Aug 9, 2026
Forecast Valid:
1pm CDT Aug 9, 2026-6pm CDT Aug 15, 2026
 
Forecast Discussion
 
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Additional Resources

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation