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.

Partly Cloudy

89°F

32°C

Humidity 57%
Wind Speed SE 14 mph
Barometer 29.80 in (1008.4 mb)
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Heat Index96°F (36°C)
Last update 22 Sep 7:56 pm CDT
Extended Forecast for

San Marcos TX

  • Tonight

    Tonight: A 20 percent chance of showers and thunderstorms before 9pm. Increasing clouds, with a low around 75. South wind 5 to 10 mph.

    Low: 75 °F

    Slight Chance
    T-storms then
    Partly Cloudy

  • Tuesday

    Tuesday: Mostly cloudy, then gradually becoming sunny, with a high near 98. Heat index values as high as 104. South wind 5 to 10 mph, with gusts as high as 20 mph.

    High: 98 °F

    Decreasing
    Clouds

  • Tuesday Night

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

    Low: 75 °F

    Mostly Clear

  • Wednesday

    Wednesday: A chance of showers before 10am, then a chance of showers and thunderstorms between 10am and 1pm, then showers likely and possibly a thunderstorm after 1pm. Mostly sunny, with a high near 93. South southwest wind around 5 mph becoming north in the afternoon. Chance of precipitation is 70%.

    High: 93 °F

    Showers
    Likely

  • Wednesday Night

    Wednesday Night: A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 71. North northeast wind around 5 mph becoming calm.

    Low: 71 °F

    Chance
    T-storms

  • Thursday

    Thursday: A chance of showers and thunderstorms before 4pm, then a slight chance of showers. Mostly sunny, with a high near 88. North wind 5 to 10 mph. Chance of precipitation is 30%.

    High: 88 °F

    Chance
    Showers

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 65. North wind around 5 mph becoming calm in the evening.

    Low: 65 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 90. Northeast wind around 5 mph.

    High: 90 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 63. East northeast wind around 5 mph becoming calm in the evening.

    Low: 63 °F

    Mostly Clear

Detailed Forecast

Tonight
A 20 percent chance of showers and thunderstorms before 9pm. Increasing clouds, with a low around 75. South wind 5 to 10 mph.
Tuesday
Mostly cloudy, then gradually becoming sunny, with a high near 98. Heat index values as high as 104. South wind 5 to 10 mph, with gusts as high as 20 mph.
Tuesday Night
Mostly clear, with a low around 75. South southeast wind 5 to 10 mph.
Wednesday
A chance of showers before 10am, then a chance of showers and thunderstorms between 10am and 1pm, then showers likely and possibly a thunderstorm after 1pm. Mostly sunny, with a high near 93. South southwest wind around 5 mph becoming north in the afternoon. Chance of precipitation is 70%.
Wednesday Night
A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 71. North northeast wind around 5 mph becoming calm.
Thursday
A chance of showers and thunderstorms before 4pm, then a slight chance of showers. Mostly sunny, with a high near 88. North wind 5 to 10 mph. Chance of precipitation is 30%.
Thursday Night
Mostly clear, with a low around 65. North wind around 5 mph becoming calm in the evening.
Friday
Sunny, with a high near 90. Northeast wind around 5 mph.
Friday Night
Mostly clear, with a low around 63. East northeast wind around 5 mph becoming calm in the evening.
Saturday
Sunny, with a high near 91.
Saturday Night
Mostly clear, with a low around 64.
Sunday
Mostly sunny, with a high near 90.
Sunday Night
Partly cloudy, with a low around 66.
Monday
A 20 percent chance of showers. Mostly sunny, with a high near 89.
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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 Sep 22, 2025
Forecast Valid:
8pm CDT Sep 22, 2025-6pm CDT Sep 29, 2025
 
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Additional Resources

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation