National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Hazardous Weather Conditions

Current conditions at

San Marcos, San Marcos Municipal Airport (KHYI)

Lat: 29.89°NLon: 97.86°WElev: 597ft.

Fair

80°F

27°C

Humidity 64%
Wind Speed S 9 mph
Barometer 30.03 in (1016.0 mb)
Dewpoint 67°F (19°C)
Visibility 10.00 mi
Heat Index82°F (28°C)
Last update 25 Aug 12:56 am CDT
Extended Forecast for

San Marcos Municipal Airport TX

Heat Advisory August 25, 01:45am until August 26, 07:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 25, 01:45am until August 26, 07:00pm

    NOW until 7:00pm Wed

    Heat Advisory

  • Overnight

    Low: 75 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny and hot, with a high near 103. South southwest wind around 5 mph.

    High: 103 °F

    Hot

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 76. South southeast wind 5 to 10 mph.

    Low: 76 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny and hot, with a high near 103. Heat index values as high as 106. Southwest wind around 5 mph.

    High: 103 °F

    Hot

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 76. South wind around 5 mph.

    Low: 76 °F

    Partly Cloudy

  • Thursday

    Thursday: A 30 percent chance of showers and thunderstorms after 1pm. Mostly sunny and hot, with a high near 101. Southwest wind around 5 mph becoming calm in the morning.

    High: 101 °F

    Mostly Sunny
    then Chance
    T-storms

  • Thursday Night

    Thursday Night: A 30 percent chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 76. East wind around 5 mph becoming calm.

    Low: 76 °F

    Chance
    T-storms then
    Chance
    Showers

  • Friday

    Friday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny and hot, with a high near 99. Calm wind becoming east around 5 mph in the afternoon.

    High: 99 °F

    Sunny then
    Slight Chance
    T-storms

Detailed Forecast

Overnight
Mostly clear, with a low around 75. South southwest wind 5 to 10 mph.
Tuesday
Sunny and hot, with a high near 103. South southwest wind around 5 mph.
Tuesday Night
Mostly clear, with a low around 76. South southeast wind 5 to 10 mph.
Wednesday
Sunny and hot, with a high near 103. Heat index values as high as 106. Southwest wind around 5 mph.
Wednesday Night
Partly cloudy, with a low around 76. South wind around 5 mph.
Thursday
A 30 percent chance of showers and thunderstorms after 1pm. Mostly sunny and hot, with a high near 101. Southwest wind around 5 mph becoming calm in the morning.
Thursday Night
A 30 percent chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 76. East wind around 5 mph becoming calm.
Friday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny and hot, with a high near 99. Calm wind becoming east around 5 mph in the afternoon.
Friday Night
A 20 percent chance of showers and thunderstorms before 1am. Mostly clear, with a low around 76. East southeast wind around 5 mph becoming calm in the evening.
Saturday
Sunny, with a high near 98.
Saturday Night
Mostly clear, with a low around 76.
Sunday
Sunny, with a high near 97.
Sunday Night
Mostly clear, with a low around 75.
Monday
Sunny, with a high near 97.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
San Marcos Municipal Airport TX
 29.88°N 97.89°W (Elev. 597 ft)
Last Update:
1:30 am CDT Aug 25, 2026
Forecast Valid:
1am CDT Aug 25, 2026-6pm CDT Aug 31, 2026
 
Forecast Discussion
 
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Additional Resources

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High Temperature

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Chance of Precipitation