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 79%
Wind Speed SE 18 G 24 mph
Barometer 29.82 in (1008.9 mb)
Dewpoint 75°F (24°C)
Visibility 9.00 mi
Heat Index89°F (32°C)
Last update 17 May 10:56 am CDT
Extended Forecast for

San Marcos TX

  • Today

    Today: Mostly cloudy, with a high near 91. South southeast wind 15 to 20 mph, with gusts as high as 30 mph.

    High: 91 °F

    Mostly Cloudy

  • Tonight

    Tonight: Mostly cloudy, with a low around 78. South southeast wind around 15 mph, with gusts as high as 30 mph.

    Low: 78 °F

    Mostly Cloudy

  • Monday

    Monday: Mostly cloudy, with a high near 92. South southeast wind 15 to 20 mph, with gusts as high as 30 mph.

    High: 92 °F

    Mostly Cloudy

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 78. South southeast wind 10 to 15 mph, with gusts as high as 25 mph.

    Low: 78 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: A 40 percent chance of showers and thunderstorms after 1pm. Mostly cloudy, with a high near 91. South southeast wind around 10 mph, with gusts as high as 20 mph.

    High: 91 °F

    Mostly Cloudy
    then Chance
    T-storms

  • Tuesday Night

    Tuesday Night: Showers and thunderstorms likely before 10pm, then showers likely and possibly a thunderstorm between 10pm and 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 74. Southeast wind 5 to 15 mph, with gusts as high as 20 mph. Chance of precipitation is 60%.

    Low: 74 °F

    T-storms
    Likely then
    Showers
    Likely

  • Wednesday

    Wednesday: Showers and thunderstorms likely, mainly after 1pm. Mostly cloudy, with a high near 86. Southeast wind 5 to 10 mph. Chance of precipitation is 60%.

    High: 86 °F

    T-storms
    Likely

  • Wednesday Night

    Wednesday Night: A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 72. East southeast wind 5 to 10 mph.

    Low: 72 °F

    Chance
    T-storms

  • Thursday

    Thursday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Mostly cloudy, with a high near 82. East wind around 5 mph. Chance of precipitation is 70%.

    High: 82 °F

    Showers
    Likely

Detailed Forecast

Today
Mostly cloudy, with a high near 91. South southeast wind 15 to 20 mph, with gusts as high as 30 mph.
Tonight
Mostly cloudy, with a low around 78. South southeast wind around 15 mph, with gusts as high as 30 mph.
Monday
Mostly cloudy, with a high near 92. South southeast wind 15 to 20 mph, with gusts as high as 30 mph.
Monday Night
Mostly cloudy, with a low around 78. South southeast wind 10 to 15 mph, with gusts as high as 25 mph.
Tuesday
A 40 percent chance of showers and thunderstorms after 1pm. Mostly cloudy, with a high near 91. South southeast wind around 10 mph, with gusts as high as 20 mph.
Tuesday Night
Showers and thunderstorms likely before 10pm, then showers likely and possibly a thunderstorm between 10pm and 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 74. Southeast wind 5 to 15 mph, with gusts as high as 20 mph. Chance of precipitation is 60%.
Wednesday
Showers and thunderstorms likely, mainly after 1pm. Mostly cloudy, with a high near 86. Southeast wind 5 to 10 mph. Chance of precipitation is 60%.
Wednesday Night
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 72. East southeast wind 5 to 10 mph.
Thursday
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Mostly cloudy, with a high near 82. East wind around 5 mph. Chance of precipitation is 70%.
Thursday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 70. Chance of precipitation is 70%.
Friday
Showers and thunderstorms likely. Mostly cloudy, with a high near 82. Chance of precipitation is 70%.
Friday Night
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 69.
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 97.91°W (Elev. 597 ft)
Last Update:
11:32 am CDT May 17, 2026
Forecast Valid:
11am 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