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

82°F

28°C

Humidity 72%
Wind Speed S 7 mph
Barometer 30.02 in (1016.0 mb)
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Heat Index87°F (31°C)
Last update 11 Jul 7:56 pm CDT
Extended Forecast for

San Marcos TX

  • Tonight

    Tonight: A 20 percent chance of showers and thunderstorms before 10pm. Partly cloudy, with a low around 75. South southeast wind around 5 mph becoming calm in the evening.

    Low: 75 °F

    Slight Chance
    T-storms then
    Partly Cloudy

  • Sunday

    Sunday: A 30 percent chance of showers and thunderstorms, mainly after 4pm. Mostly cloudy, then gradually becoming sunny, with a high near 92. Heat index values as high as 100. Calm wind becoming south southeast around 5 mph in the afternoon.

    High: 92 °F

    Partly Sunny
    then Chance
    T-storms

  • Sunday Night

    Sunday Night: A 30 percent chance of showers and thunderstorms before 7pm. Partly cloudy, with a low around 75. Southeast wind 5 to 10 mph becoming light south in the evening.

    Low: 75 °F

    Chance
    T-storms then
    Partly Cloudy

  • Monday

    Monday: Showers likely and possibly a thunderstorm after 1pm. Partly sunny, with a high near 91. Calm wind becoming south southeast around 5 mph in the afternoon. Chance of precipitation is 60%.

    High: 91 °F

    Partly Sunny
    then Showers
    Likely

  • Monday Night

    Monday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 74. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 60%.

    Low: 74 °F

    Chance
    Showers then
    Showers
    Likely

  • Tuesday

    Tuesday: Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 88. Calm wind becoming southeast around 5 mph in the afternoon. Chance of precipitation is 70%.

    High: 88 °F

    Showers
    Likely

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers and thunderstorms, mainly after 1am. Mostly cloudy, with a low around 73. East southeast wind around 5 mph becoming calm in the evening.

    Low: 73 °F

    Slight Chance
    T-storms then
    Chance
    Showers

  • Wednesday

    Wednesday: A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 86. Calm wind becoming southeast around 5 mph in the afternoon.

    High: 86 °F

    Chance
    Showers then
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A 30 percent chance of showers and thunderstorms, mainly after 1am. Mostly cloudy, with a low around 72. Southeast wind around 5 mph.

    Low: 72 °F

    Slight Chance
    T-storms then
    Chance
    Showers

Detailed Forecast

Tonight
A 20 percent chance of showers and thunderstorms before 10pm. Partly cloudy, with a low around 75. South southeast wind around 5 mph becoming calm in the evening.
Sunday
A 30 percent chance of showers and thunderstorms, mainly after 4pm. Mostly cloudy, then gradually becoming sunny, with a high near 92. Heat index values as high as 100. Calm wind becoming south southeast around 5 mph in the afternoon.
Sunday Night
A 30 percent chance of showers and thunderstorms before 7pm. Partly cloudy, with a low around 75. Southeast wind 5 to 10 mph becoming light south in the evening.
Monday
Showers likely and possibly a thunderstorm after 1pm. Partly sunny, with a high near 91. Calm wind becoming south southeast around 5 mph in the afternoon. Chance of precipitation is 60%.
Monday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 74. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 60%.
Tuesday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 88. Calm wind becoming southeast around 5 mph in the afternoon. Chance of precipitation is 70%.
Tuesday Night
A 30 percent chance of showers and thunderstorms, mainly after 1am. Mostly cloudy, with a low around 73. East southeast wind around 5 mph becoming calm in the evening.
Wednesday
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 86. Calm wind becoming southeast around 5 mph in the afternoon.
Wednesday Night
A 30 percent chance of showers and thunderstorms, mainly after 1am. Mostly cloudy, with a low around 72. Southeast wind around 5 mph.
Thursday
A slight chance of showers, with thunderstorms also possible after 1pm. Mostly cloudy, with a high near 90. Chance of precipitation is 20%.
Thursday Night
Mostly cloudy, with a low around 74.
Friday
A 20 percent chance of showers and thunderstorms. Partly sunny, with a high near 92.
Friday Night
Partly cloudy, with a low around 74.
Saturday
Mostly sunny, with a high near 93.
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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:
6:46 pm CDT Jul 11, 2026
Forecast Valid:
8pm CDT Jul 11, 2026-6pm CDT Jul 18, 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