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

77°F

25°C

Humidity 66%
Wind Speed S 5 mph
Barometer 30.00 in (1015.0 mb)
Dewpoint 65°F (18°C)
Visibility 10.00 mi
Heat Index79°F (26°C)
Last update 23 Aug 3:56 am CDT
Extended Forecast for

San Marcos TX

Heat Advisory August 23, 04:07am until August 26, 07:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 23, 04:07am until August 26, 07:00pm

    NOW until 7:00pm Wed

    Heat Advisory

  • Today

    High: 105 °F

    Hot

  • Tonight

    Tonight: Mostly clear, with a low around 76. South southeast wind around 5 mph.

    Low: 76 °F

    Mostly Clear

  • Monday

    Monday: Sunny and hot, with a high near 104. Heat index values as high as 107. Southwest wind around 5 mph.

    High: 104 °F

    Hot

  • Monday Night

    Monday Night: Mostly clear, with a low around 75. South southeast wind 5 to 10 mph.

    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 77. South southeast wind around 5 mph.

    Low: 77 °F

    Mostly Clear

  • Wednesday

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

    High: 103 °F

    Hot

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 78. South southwest wind around 5 mph.

    Low: 78 °F

    Mostly Clear

Detailed Forecast

Today
Sunny and hot, with a high near 105. Southwest wind around 5 mph becoming south southeast in the afternoon.
Tonight
Mostly clear, with a low around 76. South southeast wind around 5 mph.
Monday
Sunny and hot, with a high near 104. Heat index values as high as 107. Southwest wind around 5 mph.
Monday Night
Mostly clear, with a low around 75. South southeast 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 77. South southeast wind around 5 mph.
Wednesday
Sunny and hot, with a high near 103. South southwest wind around 5 mph.
Wednesday Night
Mostly clear, with a low around 78. South southwest wind around 5 mph.
Thursday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny and hot, with a high near 103. Southwest wind around 5 mph becoming calm in the morning.
Thursday Night
Partly cloudy, with a low around 77.
Friday
Mostly sunny and hot, with a high near 101.
Friday Night
Mostly clear, with a low around 77.
Saturday
Sunny and hot, with a high near 100.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
San Marcos TX
 29.9°N 97.94°W (Elev. 597 ft)
Last Update:
2:46 am CDT Aug 23, 2026
Forecast Valid:
4am CDT Aug 23, 2026-6pm CDT Aug 29, 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