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

86°F

30°C

Humidity 46%
Wind Speed SE 5 mph
Barometer 30.04 in (1016.5 mb)
Dewpoint 63°F (17°C)
Visibility 10.00 mi
Heat Index87°F (31°C)
Last update 16 Aug 8:56 pm CDT
Extended Forecast for

San Marcos TX

  • Tonight

    Tonight: Mostly clear, with a low around 73. South southeast wind 5 to 10 mph becoming southwest after midnight. Winds could gust as high as 20 mph.

    Low: 73 °F

    Mostly Clear

  • Monday

    Monday: Sunny and hot, with a high near 100. Southwest wind around 5 mph becoming south southeast in the afternoon.

    High: 100 °F

    Hot

  • Monday Night

    Monday Night: Mostly clear, with a low around 75. South southeast wind 5 to 10 mph.

    Low: 75 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny and hot, with a high near 99. Heat index values as high as 102. South wind around 5 mph.

    High: 99 °F

    Hot

  • Tuesday Night

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

    Low: 76 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny and hot, with a high near 100. South southwest wind around 5 mph.

    High: 100 °F

    Hot

  • Wednesday Night

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

    Low: 76 °F

    Mostly Clear

  • Thursday

    Thursday: Mostly sunny and hot, with a high near 101. South wind around 5 mph.

    High: 101 °F

    Hot

  • Thursday Night

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

    Low: 76 °F

    Mostly Clear

Detailed Forecast

Tonight
Mostly clear, with a low around 73. South southeast wind 5 to 10 mph becoming southwest after midnight. Winds could gust as high as 20 mph.
Monday
Sunny and hot, with a high near 100. Southwest wind around 5 mph becoming south southeast in the afternoon.
Monday Night
Mostly clear, with a low around 75. South southeast wind 5 to 10 mph.
Tuesday
Sunny and hot, with a high near 99. Heat index values as high as 102. South wind around 5 mph.
Tuesday Night
Mostly clear, with a low around 76. South wind around 5 mph.
Wednesday
Sunny and hot, with a high near 100. South southwest wind around 5 mph.
Wednesday Night
Mostly clear, with a low around 76. South wind 5 to 10 mph, with gusts as high as 20 mph.
Thursday
Mostly sunny and hot, with a high near 101. South wind around 5 mph.
Thursday Night
Mostly clear, with a low around 76. South southeast wind 5 to 10 mph.
Friday
Sunny and hot, with a high near 100.
Friday Night
Mostly clear, with a low around 76.
Saturday
Mostly sunny and hot, with a high near 100.
Saturday Night
Mostly clear, with a low around 76.
Sunday
Sunny and hot, with a high near 99.
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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 pm CDT Aug 16, 2026
Forecast Valid:
9pm CDT Aug 16, 2026-6pm CDT Aug 23, 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