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 and Breezy

89°F

32°C

Humidity 59%
Wind Speed SE 22 G 31 mph
Barometer 29.85 in (1010.0 mb)
Dewpoint 73°F (23°C)
Visibility 10.00 mi
Heat Index97°F (36°C)
Last update 3 Sep 5:56 pm CDT
Extended Forecast for

San Marcos TX

  • Tonight

    Tonight: A slight chance of showers and thunderstorms before 7pm, then a slight chance of showers after 4am. Increasing clouds, with a low around 77. South wind 5 to 10 mph, with gusts as high as 20 mph. Chance of precipitation is 20%.

    Low: 77 °F

    Slight Chance
    T-storms then
    Slight Chance
    Showers

  • Friday

    Friday: A 30 percent chance of showers and thunderstorms, mainly between 10am and 4pm. Mostly cloudy, then gradually becoming sunny, with a high near 93. Heat index values as high as 100. South southeast wind around 5 mph.

    High: 93 °F

    Chance
    T-storms

  • Friday Night

    Friday Night: A 10 percent chance of showers and thunderstorms before 7pm. Partly cloudy, with a low around 75. East southeast wind around 5 mph becoming calm after midnight.

    Low: 75 °F

    Slight Chance
    T-storms then
    Partly Cloudy

  • Saturday

    Saturday: A 20 percent chance of showers and thunderstorms after 1pm. Mostly cloudy, then gradually becoming sunny, with a high near 95. Heat index values as high as 102. Calm wind becoming southeast around 5 mph in the afternoon.

    High: 95 °F

    Partly Sunny
    then Slight
    Chance
    T-storms

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 75. Southeast wind around 5 mph becoming calm in the evening.

    Low: 75 °F

    Partly Cloudy

  • Sunday

    Sunday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 96. Calm wind becoming east southeast around 5 mph.

    High: 96 °F

    Sunny then
    Slight Chance
    T-storms

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 76. Southeast wind around 5 mph becoming calm in the evening.

    Low: 76 °F

    Mostly Clear

  • Labor Day

    Labor Day: Sunny, with a high near 96. Calm wind becoming southeast around 5 mph in the afternoon.

    High: 96 °F

    Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 75. Southeast wind around 5 mph becoming calm after midnight.

    Low: 75 °F

    Mostly Clear

Detailed Forecast

Tonight
A slight chance of showers and thunderstorms before 7pm, then a slight chance of showers after 4am. Increasing clouds, with a low around 77. South wind 5 to 10 mph, with gusts as high as 20 mph. Chance of precipitation is 20%.
Friday
A 30 percent chance of showers and thunderstorms, mainly between 10am and 4pm. Mostly cloudy, then gradually becoming sunny, with a high near 93. Heat index values as high as 100. South southeast wind around 5 mph.
Friday Night
A 10 percent chance of showers and thunderstorms before 7pm. Partly cloudy, with a low around 75. East southeast wind around 5 mph becoming calm after midnight.
Saturday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly cloudy, then gradually becoming sunny, with a high near 95. Heat index values as high as 102. Calm wind becoming southeast around 5 mph in the afternoon.
Saturday Night
Partly cloudy, with a low around 75. Southeast wind around 5 mph becoming calm in the evening.
Sunday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 96. Calm wind becoming east southeast around 5 mph.
Sunday Night
Mostly clear, with a low around 76. Southeast wind around 5 mph becoming calm in the evening.
Labor Day
Sunny, with a high near 96. Calm wind becoming southeast around 5 mph in the afternoon.
Monday Night
Mostly clear, with a low around 75. Southeast wind around 5 mph becoming calm after midnight.
Tuesday
A 30 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 96.
Tuesday Night
Partly cloudy, with a low around 75.
Wednesday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 95.
Wednesday Night
Partly cloudy, with a low around 74.
Thursday
Mostly sunny, with a high near 95.
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 pm CDT Sep 3, 2026
Forecast Valid:
6pm CDT Sep 3, 2026-6pm CDT Sep 10, 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