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

79°F

26°C

Humidity 69%
Wind Speed NE 7 mph
Barometer 30.04 in (1016.8 mb)
Dewpoint 68°F (20°C)
Visibility 10.00 mi
Heat Index81°F (27°C)
Last update 20 May 12:56 pm CDT
Extended Forecast for

San Marcos TX

  • This Afternoon

    This Afternoon: Partly sunny, with a high near 82. East southeast wind 5 to 10 mph.

    High: 82 °F

    Partly Sunny

  • Tonight

    Tonight: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 4am. Mostly cloudy, with a low around 71. East southeast wind around 5 mph. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.

    Low: 71 °F

    Chance
    T-storms then
    Showers
    Likely

  • Thursday

    Thursday: Showers likely and possibly a thunderstorm before 7am, then a chance of showers and thunderstorms after 7am. Mostly cloudy, with a high near 80. Northeast wind around 5 mph becoming south in the morning. Chance of precipitation is 60%. New rainfall amounts between a quarter and half of an inch possible.

    High: 80 °F

    Showers
    Likely then
    Chance
    T-storms

  • Thursday Night

    Thursday Night: A 30 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 69. Southeast wind around 5 mph.

    Low: 69 °F

    Chance
    T-storms then
    Chance
    Showers

  • Friday

    Friday: A 40 percent chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 85. South wind around 5 mph.

    High: 85 °F

    Mostly Cloudy
    then Chance
    T-storms

  • Friday Night

    Friday Night: A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 71. Southeast wind around 5 mph.

    Low: 71 °F

    Chance
    T-storms

  • Saturday

    Saturday: A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1pm. High near 82. South southeast wind around 5 mph. Chance of precipitation is 80%.

    High: 82 °F

    Chance
    T-storms then
    T-storms

  • Saturday Night

    Saturday Night: Showers and possibly a thunderstorm. Low around 69. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 80%.

    Low: 69 °F

    Showers

  • Sunday

    Sunday: Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 83. Calm wind becoming north northeast around 5 mph in the afternoon. Chance of precipitation is 60%.

    High: 83 °F

    Showers
    Likely

Detailed Forecast

This Afternoon
Partly sunny, with a high near 82. East southeast wind 5 to 10 mph.
Tonight
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 4am. Mostly cloudy, with a low around 71. East southeast wind around 5 mph. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.
Thursday
Showers likely and possibly a thunderstorm before 7am, then a chance of showers and thunderstorms after 7am. Mostly cloudy, with a high near 80. Northeast wind around 5 mph becoming south in the morning. Chance of precipitation is 60%. New rainfall amounts between a quarter and half of an inch possible.
Thursday Night
A 30 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 69. Southeast wind around 5 mph.
Friday
A 40 percent chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 85. South wind around 5 mph.
Friday Night
A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 71. Southeast wind around 5 mph.
Saturday
A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1pm. High near 82. South southeast wind around 5 mph. Chance of precipitation is 80%.
Saturday Night
Showers and possibly a thunderstorm. Low around 69. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 80%.
Sunday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 83. Calm wind becoming north northeast around 5 mph in the afternoon. Chance of precipitation is 60%.
Sunday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 69.
Memorial Day
A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 85.
Monday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 70.
Tuesday
A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 84.
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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:
12:42 pm CDT May 20, 2026
Forecast Valid:
1pm CDT May 20, 2026-6pm CDT May 26, 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