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.

Thunderstorm in Vicinity Light Rain

68°F

20°C

Humidity 87%
Wind Speed SE 9 mph
Barometer 30.04 in (1016.3 mb)
Dewpoint 64°F (18°C)
Visibility 10.00 mi
Last update 20 May 3:56 am CDT
Extended Forecast for

3 Miles WSW San Marcos TX

  • Overnight

    Overnight: A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 66. Northeast wind around 15 mph.

    Low: 66 °F

    Chance
    Showers

  • Wednesday

    Wednesday: A 30 percent chance of showers and thunderstorms before 7am. Partly sunny, with a high near 83. East northeast wind 5 to 10 mph.

    High: 83 °F

    Chance
    Showers then
    Partly Sunny

  • Wednesday Night

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

    Low: 70 °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. East northeast wind around 5 mph becoming south in the morning. Chance of precipitation is 60%.

    High: 80 °F

    Showers
    Likely then
    Chance
    T-storms

  • Thursday Night

    Thursday Night: A 20 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 69. Southeast wind around 5 mph becoming calm in the evening.

    Low: 69 °F

    Slight Chance
    T-storms

  • 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

Detailed Forecast

Overnight
A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 66. Northeast wind around 15 mph.
Wednesday
A 30 percent chance of showers and thunderstorms before 7am. Partly sunny, with a high near 83. East northeast wind 5 to 10 mph.
Wednesday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 4am. Mostly cloudy, with a low around 70. East 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. East northeast wind around 5 mph becoming south in the morning. Chance of precipitation is 60%.
Thursday Night
A 20 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 69. Southeast wind around 5 mph becoming calm in the evening.
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 82. Chance of precipitation is 60%.
Sunday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 68.
Memorial Day
A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 84.
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:
3 Miles WSW San Marcos TX
 29.86°N 97.97°W (Elev. 646 ft)
Last Update:
4:22 am CDT May 20, 2026
Forecast Valid:
4am 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