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.

Fog/Mist

79°F

26°C

Humidity 90%
Wind Speed Calm
Barometer 30.09 in (1018.3 mb)
Dewpoint 76°F (24°C)
Visibility 5.00 mi
Heat Index83°F (28°C)
Last update 29 Aug 9:56 am CDT
Extended Forecast for

San Marcos TX

  • Today

    Today: Sunny, with a high near 98. Heat index values as high as 103. Calm wind becoming south southeast around 5 mph in the afternoon.

    High: 98 °F

    Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 75. South southeast wind around 5 mph.

    Low: 75 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 97. Heat index values as high as 100. Calm wind becoming south around 5 mph in the morning.

    High: 97 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 74. South southeast wind 5 to 10 mph.

    Low: 74 °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.

    Low: 75 °F

    Mostly Clear

  • Tuesday

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

    High: 97 °F

    Sunny

  • Tuesday Night

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

    Low: 75 °F

    Mostly Clear

  • Wednesday

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

    High: 97 °F

    Sunny

Detailed Forecast

Today
Sunny, with a high near 98. Heat index values as high as 103. Calm wind becoming south southeast around 5 mph in the afternoon.
Tonight
Mostly clear, with a low around 75. South southeast wind around 5 mph.
Sunday
Sunny, with a high near 97. Heat index values as high as 100. Calm wind becoming south around 5 mph in the morning.
Sunday Night
Mostly clear, with a low around 74. South 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.
Tuesday
Sunny, with a high near 97. Calm wind becoming south southeast around 5 mph in the morning.
Tuesday Night
Mostly clear, with a low around 75. Southeast wind 5 to 10 mph.
Wednesday
Sunny, with a high near 97. Calm wind becoming south around 5 mph in the afternoon.
Wednesday Night
Mostly clear, with a low around 75.
Thursday
A 20 percent chance of showers and thunderstorms. Sunny, with a high near 97.
Thursday Night
A 20 percent chance of showers and thunderstorms. Mostly clear, with a low around 75.
Friday
Mostly sunny, with a high near 98.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
San Marcos TX
 29.88°N 97.94°W (Elev. 577 ft)
Last Update:
10:16 am CDT Aug 29, 2026
Forecast Valid:
10am CDT Aug 29, 2026-6pm CDT Sep 4, 2026
 
Forecast Discussion
 
Get as KML Get as XML

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