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

29°C

85°F

Humidity 75%
Wind Speed S 11 km/h
Barometer 1014.4 mb (29.98 in)
Dewpoint 24°C (76°F)
Visibility 16 km
Heat Index35°C (95°F)
Last update 5 Sep 9:56 am CDT
Extended Forecast for

San Marcos TX

  • Today

    Today: Mostly sunny, with a high near 36. Southeast wind around 10 km/h.

    High: 36 °C

    Mostly Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 24. East southeast wind 5 to 15 km/h becoming south southwest after midnight.

    Low: 24 °C

    Partly Cloudy

  • Sunday

    Sunday: A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 36. Heat index values as high as 40. South wind 5 to 10 km/h becoming east in the afternoon.

    High: 36 °C

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 24. East southeast wind 5 to 10 km/h becoming south southwest after midnight.

    Low: 24 °C

    Partly Cloudy

  • Labor Day

    Labor Day: Mostly sunny and hot, with a high near 37. South southwest wind 5 to 10 km/h becoming southeast in the afternoon.

    High: 37 °C

    Hot

  • Monday Night

    Monday Night: Mostly clear, with a low around 24. South wind 5 to 10 km/h.

    Low: 24 °C

    Mostly Clear

  • Tuesday

    Tuesday: Sunny, with a high near 36. Calm wind becoming south southeast 5 to 10 km/h in the afternoon.

    High: 36 °C

    Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 24. Southeast wind 5 to 10 km/h becoming calm after midnight.

    Low: 24 °C

    Mostly Clear

  • Wednesday

    Wednesday: A slight chance of showers, with thunderstorms also possible after 1pm. Mostly sunny, with a high near 36. Calm wind becoming south southeast 5 to 10 km/h in the afternoon. Chance of precipitation is 20%.

    High: 36 °C

    Slight Chance
    Showers then
    Slight Chance
    T-storms

Detailed Forecast

Today
Mostly sunny, with a high near 36. Southeast wind around 10 km/h.
Tonight
Partly cloudy, with a low around 24. East southeast wind 5 to 15 km/h becoming south southwest after midnight.
Sunday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 36. Heat index values as high as 40. South wind 5 to 10 km/h becoming east in the afternoon.
Sunday Night
Partly cloudy, with a low around 24. East southeast wind 5 to 10 km/h becoming south southwest after midnight.
Labor Day
Mostly sunny and hot, with a high near 37. South southwest wind 5 to 10 km/h becoming southeast in the afternoon.
Monday Night
Mostly clear, with a low around 24. South wind 5 to 10 km/h.
Tuesday
Sunny, with a high near 36. Calm wind becoming south southeast 5 to 10 km/h in the afternoon.
Tuesday Night
Mostly clear, with a low around 24. Southeast wind 5 to 10 km/h becoming calm after midnight.
Wednesday
A slight chance of showers, with thunderstorms also possible after 1pm. Mostly sunny, with a high near 36. Calm wind becoming south southeast 5 to 10 km/h in the afternoon. Chance of precipitation is 20%.
Wednesday Night
Partly cloudy, with a low around 23.
Thursday
Mostly sunny, with a high near 36.
Thursday Night
Mostly clear, with a low around 24.
Friday
Mostly sunny, with a high near 36.
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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 m)
Last Update:
9:42 am CDT Sep 5, 2026
Forecast Valid:
10am CDT Sep 5, 2026-6pm CDT Sep 11, 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