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.

Overcast

82°F

28°C

Humidity 77%
Wind Speed S 17 G 26 mph
Barometer 29.83 in (1009.4 mb)
Dewpoint 74°F (23°C)
Visibility 10.00 mi
Heat Index88°F (31°C)
Last update 17 May 11:56 am CDT
Extended Forecast for

San Marcos TX

  • This Afternoon

    This Afternoon: Mostly cloudy, with a high near 90. South southeast wind around 15 mph, with gusts as high as 30 mph.

    High: 90 °F

    Mostly Cloudy

  • Tonight

    Tonight: A 20 percent chance of showers and thunderstorms before 11pm. Mostly cloudy, with a low around 77. South southeast wind 15 to 20 mph, with gusts as high as 30 mph.

    Low: 77 °F

    Slight Chance
    T-storms then
    Mostly Cloudy

  • Monday

    Monday: Mostly cloudy, with a high near 90. South southeast wind 15 to 20 mph, with gusts as high as 30 mph.

    High: 90 °F

    Mostly Cloudy

  • Monday Night

    Monday Night: A 20 percent chance of showers and thunderstorms before 10pm. Mostly cloudy, with a low around 78. South southeast wind 10 to 15 mph, with gusts as high as 25 mph.

    Low: 78 °F

    Slight Chance
    T-storms then
    Mostly Cloudy

  • Tuesday

    Tuesday: A 50 percent chance of showers and thunderstorms after 1pm. Mostly cloudy, with a high near 89. South southeast wind 10 to 15 mph, with gusts as high as 25 mph.

    High: 89 °F

    Mostly Cloudy
    then Chance
    T-storms

  • Tuesday Night

    Tuesday Night: Showers likely and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 73. Southeast wind 5 to 15 mph, with gusts as high as 20 mph. Chance of precipitation is 60%.

    Low: 73 °F

    Showers
    Likely

  • Wednesday

    Wednesday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Mostly cloudy, with a high near 85. East southeast wind 5 to 10 mph. Chance of precipitation is 60%.

    High: 85 °F

    Chance
    T-storms then
    Showers
    Likely

  • Wednesday Night

    Wednesday Night: A 30 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 72. East southeast wind 5 to 10 mph.

    Low: 72 °F

    Chance
    T-storms

  • Thursday

    Thursday: Showers and possibly a thunderstorm. High near 81. East southeast wind 5 to 10 mph. Chance of precipitation is 80%.

    High: 81 °F

    Showers
    Likely then
    T-storms

Detailed Forecast

This Afternoon
Mostly cloudy, with a high near 90. South southeast wind around 15 mph, with gusts as high as 30 mph.
Tonight
A 20 percent chance of showers and thunderstorms before 11pm. Mostly cloudy, with a low around 77. South southeast wind 15 to 20 mph, with gusts as high as 30 mph.
Monday
Mostly cloudy, with a high near 90. South southeast wind 15 to 20 mph, with gusts as high as 30 mph.
Monday Night
A 20 percent chance of showers and thunderstorms before 10pm. Mostly cloudy, with a low around 78. South southeast wind 10 to 15 mph, with gusts as high as 25 mph.
Tuesday
A 50 percent chance of showers and thunderstorms after 1pm. Mostly cloudy, with a high near 89. South southeast wind 10 to 15 mph, with gusts as high as 25 mph.
Tuesday Night
Showers likely and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 73. Southeast wind 5 to 15 mph, with gusts as high as 20 mph. Chance of precipitation is 60%.
Wednesday
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Mostly cloudy, with a high near 85. East southeast wind 5 to 10 mph. Chance of precipitation is 60%.
Wednesday Night
A 30 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 72. East southeast wind 5 to 10 mph.
Thursday
Showers and possibly a thunderstorm. High near 81. East southeast wind 5 to 10 mph. Chance of precipitation is 80%.
Thursday Night
Showers and possibly a thunderstorm. Low around 69. Chance of precipitation is 80%.
Friday
Showers and thunderstorms likely. Mostly cloudy, with a high near 81. Chance of precipitation is 70%.
Friday Night
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 68.
Saturday
A 50 percent chance of showers and thunderstorms. Partly sunny, with a high near 82.
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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:
12:20 pm CDT May 17, 2026
Forecast Valid:
12pm CDT May 17, 2026-6pm CDT May 23, 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