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 Light Rain

68°F

20°C

Humidity 93%
Wind Speed E 6 mph
Barometer 30.13 in (1019.7 mb)
Dewpoint 66°F (19°C)
Visibility 10.00 mi
Last update 20 May 1:56 am CDT
Extended Forecast for

San Marcos TX

  • Overnight

    Overnight: Showers likely and possibly a thunderstorm before 4am, then a chance of showers and thunderstorms after 4am. Mostly cloudy, with a low around 66. Northeast wind around 5 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    Low: 66 °F

    Showers
    Likely

  • Wednesday

    Wednesday: A 30 percent chance of showers and thunderstorms before 7am. Partly sunny, with a high near 82. East southeast wind around 5 mph.

    High: 82 °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 71. East southeast wind around 5 mph. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.

    Low: 71 °F

    Chance
    T-storms then
    Showers
    Likely

  • Thursday

    Thursday: Showers and thunderstorms likely before 1pm, then showers likely and possibly a thunderstorm between 1pm and 4pm, then a chance of showers and thunderstorms after 4pm. Mostly cloudy, with a high near 80. Northeast wind around 5 mph becoming south in the morning. Chance of precipitation is 70%.

    High: 80 °F

    Showers
    Likely

  • Thursday Night

    Thursday Night: A 40 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 69. Southeast wind around 5 mph.

    Low: 69 °F

    Chance
    T-storms then
    Chance
    Showers

  • 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
Showers likely and possibly a thunderstorm before 4am, then a chance of showers and thunderstorms after 4am. Mostly cloudy, with a low around 66. Northeast wind around 5 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Wednesday
A 30 percent chance of showers and thunderstorms before 7am. Partly sunny, with a high near 82. East southeast wind around 5 mph.
Wednesday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 4am. Mostly cloudy, with a low around 71. East southeast wind around 5 mph. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.
Thursday
Showers and thunderstorms likely before 1pm, then showers likely and possibly a thunderstorm between 1pm and 4pm, then a chance of showers and thunderstorms after 4pm. Mostly cloudy, with a high near 80. Northeast wind around 5 mph becoming south in the morning. Chance of precipitation is 70%.
Thursday Night
A 40 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 69. Southeast wind around 5 mph.
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 83. Chance of precipitation is 60%.
Sunday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 69.
Memorial Day
A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 85.
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.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
San Marcos TX
 29.88°N 97.94°W (Elev. 577 ft)
Last Update:
1:54 am CDT May 20, 2026
Forecast Valid:
2am CDT May 20, 2026-6pm CDT May 26, 2026
 
Forecast Discussion
 
Get as KML Get as XML

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