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

77°F

25°C

Humidity 85%
Wind Speed SE 3 mph
Barometer 30.02 in (1015.5 mb)
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Heat Index78°F (26°C)
Last update 1 Sep 1:56 am CDT
Extended Forecast for

San Marcos TX

  • Overnight

    Overnight: Mostly clear, with a low around 75. South wind around 5 mph becoming calm.

    Low: 75 °F

    Mostly Clear

  • Tuesday

    Tuesday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 97. Heat index values as high as 103. Calm wind.

    High: 97 °F

    Sunny then
    Slight Chance
    T-storms

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 77. East northeast wind around 5 mph becoming calm.

    Low: 77 °F

    Partly Cloudy

  • Wednesday

    Wednesday: A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 98. Heat index values as high as 103. Calm wind becoming southwest around 5 mph.

    High: 98 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A slight chance of showers and thunderstorms. Partly cloudy, with a low around 76. South wind around 5 mph. Chance of precipitation is 20%.

    Low: 76 °F

    Slight Chance
    T-storms then
    Slight Chance
    Showers

  • Thursday

    Thursday: A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 97. South wind around 5 mph.

    High: 97 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Thursday Night

    Thursday Night: A slight chance of showers and thunderstorms before 10pm, then a slight chance of showers between 10pm and 1am, then a chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 75. Southeast wind 5 to 10 mph. Chance of precipitation is 30%.

    Low: 75 °F

    Slight Chance
    T-storms then
    Chance
    Showers

  • Friday

    Friday: Mostly sunny, with a high near 96. South wind around 5 mph.

    High: 96 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 75. Southeast wind 5 to 10 mph becoming light south after midnight.

    Low: 75 °F

    Mostly Clear

Detailed Forecast

Overnight
Mostly clear, with a low around 75. South wind around 5 mph becoming calm.
Tuesday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 97. Heat index values as high as 103. Calm wind.
Tuesday Night
Partly cloudy, with a low around 77. East northeast wind around 5 mph becoming calm.
Wednesday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 98. Heat index values as high as 103. Calm wind becoming southwest around 5 mph.
Wednesday Night
A slight chance of showers and thunderstorms. Partly cloudy, with a low around 76. South wind around 5 mph. Chance of precipitation is 20%.
Thursday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 97. South wind around 5 mph.
Thursday Night
A slight chance of showers and thunderstorms before 10pm, then a slight chance of showers between 10pm and 1am, then a chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 75. Southeast wind 5 to 10 mph. Chance of precipitation is 30%.
Friday
Mostly sunny, with a high near 96. South wind around 5 mph.
Friday Night
Mostly clear, with a low around 75. Southeast wind 5 to 10 mph becoming light south after midnight.
Saturday
Mostly sunny, with a high near 96.
Saturday Night
Mostly clear, with a low around 75.
Sunday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 96.
Sunday Night
Mostly clear, with a low around 75.
Labor Day
Sunny, with a high near 96.
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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:
1:36 am CDT Sep 1, 2026
Forecast Valid:
2am CDT Sep 1, 2026-6pm CDT Sep 7, 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