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 70%
Wind Speed Vrbl 7 mph
Barometer 30.15 in (1019.9 mb)
Dewpoint 75°F (24°C)
Visibility 10.00 mi
Heat Index95°F (35°C)
Last update 17 Aug 9:56 am CDT
Extended Forecast for

San Marcos TX

  • Today

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

    High: 100 °F

    Hot

  • Tonight

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

    Low: 76 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny and hot, with a high near 99. Heat index values as high as 102. Calm wind becoming south around 5 mph in the afternoon.

    High: 99 °F

    Hot

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 77. South wind around 5 mph.

    Low: 77 °F

    Mostly Clear

  • Wednesday

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

    High: 99 °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: Sunny and hot, with a high near 100. South wind around 5 mph.

    High: 100 °F

    Hot

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 77. South southeast wind 5 to 10 mph.

    Low: 77 °F

    Mostly Clear

  • Friday

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

    High: 100 °F

    Hot

Detailed Forecast

Today
Sunny and hot, with a high near 100. Southwest wind around 5 mph becoming south southeast in the afternoon.
Tonight
Mostly clear, with a low around 76. South southeast wind 5 to 10 mph.
Tuesday
Sunny and hot, with a high near 99. Heat index values as high as 102. Calm wind becoming south around 5 mph in the afternoon.
Tuesday Night
Mostly clear, with a low around 77. South wind around 5 mph.
Wednesday
Sunny and hot, with a high near 99. 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
Sunny and hot, with a high near 100. South wind around 5 mph.
Thursday Night
Mostly clear, with a low around 77. South southeast wind 5 to 10 mph.
Friday
Sunny and hot, with a high near 100. South southwest wind around 5 mph.
Friday Night
Mostly clear, with a low around 77.
Saturday
Sunny and hot, with a high near 100.
Saturday Night
Mostly clear, with a low around 77.
Sunday
Sunny and hot, with a high near 100.
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:
6:42 am CDT Aug 17, 2026
Forecast Valid:
9am CDT Aug 17, 2026-6pm CDT Aug 23, 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