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.

Mostly Cloudy

91°F

33°C

Humidity 57%
Wind Speed SE 16 mph
Barometer 29.93 in (1012.7 mb)
Dewpoint 74°F (23°C)
Visibility 1.00 mi
Heat Index100°F (38°C)
Last update 19 May 4:56 pm CDT
Extended Forecast for

San Marcos TX

  • This Afternoon

    This Afternoon: A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 90. South southeast wind around 10 mph, with gusts as high as 20 mph.

    High: 90 °F

    Chance
    T-storms

  • Tonight

    Tonight: Showers and thunderstorms, mainly before 1am. Low around 71. Southeast wind 5 to 10 mph becoming north northwest after midnight. Chance of precipitation is 80%. New rainfall amounts between 1 and 2 inches possible.

    Low: 71 °F

    T-storms

  • Wednesday

    Wednesday: A 40 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 83. East northeast wind around 5 mph.

    High: 83 °F

    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 71. East wind around 5 mph. Chance of precipitation is 60%.

    Low: 71 °F

    Chance
    T-storms then
    Showers
    Likely

  • Thursday

    Thursday: Showers and possibly a thunderstorm. High near 81. Southeast wind around 5 mph. Chance of precipitation is 90%.

    High: 81 °F

    Showers

  • Thursday Night

    Thursday Night: Showers likely and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 70. South southeast wind around 5 mph. Chance of precipitation is 60%.

    Low: 70 °F

    Showers
    Likely

  • Friday

    Friday: A 50 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 chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 71. Southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 60%.

    Low: 71 °F

    Chance
    T-storms then
    Showers
    Likely

  • Saturday

    Saturday: A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1pm. High near 83. Calm wind becoming south southeast around 5 mph in the morning. Chance of precipitation is 80%.

    High: 83 °F

    Chance
    T-storms then
    Showers

Detailed Forecast

This Afternoon
A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 90. South southeast wind around 10 mph, with gusts as high as 20 mph.
Tonight
Showers and thunderstorms, mainly before 1am. Low around 71. Southeast wind 5 to 10 mph becoming north northwest after midnight. Chance of precipitation is 80%. New rainfall amounts between 1 and 2 inches possible.
Wednesday
A 40 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 83. East northeast wind around 5 mph.
Wednesday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 71. East wind around 5 mph. Chance of precipitation is 60%.
Thursday
Showers and possibly a thunderstorm. High near 81. Southeast wind around 5 mph. Chance of precipitation is 90%.
Thursday Night
Showers likely and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 70. South southeast wind around 5 mph. Chance of precipitation is 60%.
Friday
A 50 percent chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 85. South wind around 5 mph.
Friday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 71. Southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 60%.
Saturday
A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1pm. High near 83. Calm wind becoming south southeast around 5 mph in the morning. Chance of precipitation is 80%.
Saturday Night
Showers and possibly a thunderstorm. Low around 69. Chance of precipitation is 80%.
Sunday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 82. Chance of precipitation is 70%.
Sunday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 69.
Memorial Day
A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 83.
Monday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 70.
Tuesday
A chance of showers and thunderstorms. Mostly sunny, with a high near 85.
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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:
4:44 pm CDT May 19, 2026
Forecast Valid:
5pm CDT May 19, 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