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

85°F

29°C

Humidity 72%
Wind Speed SW 7 mph
Barometer 30.08 in (1017.6 mb)
Dewpoint 75°F (24°C)
Visibility 10.00 mi
Heat Index93°F (34°C)
Last update 26 Aug 9:56 am CDT
Extended Forecast for

3 Miles SSE San Marcos TX

Heat Advisory August 26, 10:46am until August 26, 07:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 26, 10:46am until August 26, 07:00pm

    NOW until 7:00pm Wed

    Heat Advisory

  • Today

    High: 102 °F

    Hot

  • Tonight

    Tonight: Partly cloudy, with a low around 77. South southwest wind around 5 mph.

    Low: 77 °F

    Partly Cloudy

  • Thursday

    Thursday: A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Mostly sunny and hot, with a high near 101. Heat index values as high as 108. Southwest wind around 5 mph becoming calm in the afternoon. Chance of precipitation is 40%.

    High: 101 °F

    Slight Chance
    Showers then
    Chance
    T-storms

  • Thursday Night

    Thursday Night: A chance of showers and thunderstorms. Partly cloudy, with a low around 75. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 40%.

    Low: 75 °F

    Chance
    T-storms then
    Chance
    Showers

  • Friday

    Friday: A slight chance of showers, with thunderstorms also possible after 4pm. Mostly sunny, with a high near 98. Calm wind becoming east around 5 mph. Chance of precipitation is 20%.

    High: 98 °F

    Slight Chance
    Showers then
    Slight Chance
    T-storms

  • Friday Night

    Friday Night: A slight chance of thunderstorms before 7pm. Mostly clear, with a low around 76. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 10%.

    Low: 76 °F

    Slight Chance
    T-storms then
    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 98. Calm wind becoming southeast around 5 mph in the afternoon.

    High: 98 °F

    Sunny

  • Saturday Night

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

    Low: 75 °F

    Mostly Clear

Detailed Forecast

Today
Sunny and hot, with a high near 102. Heat index values as high as 105. South wind around 5 mph.
Tonight
Partly cloudy, with a low around 77. South southwest wind around 5 mph.
Thursday
A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Mostly sunny and hot, with a high near 101. Heat index values as high as 108. Southwest wind around 5 mph becoming calm in the afternoon. Chance of precipitation is 40%.
Thursday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 75. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 40%.
Friday
A slight chance of showers, with thunderstorms also possible after 4pm. Mostly sunny, with a high near 98. Calm wind becoming east around 5 mph. Chance of precipitation is 20%.
Friday Night
A slight chance of thunderstorms before 7pm. Mostly clear, with a low around 76. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 10%.
Saturday
Sunny, with a high near 98. Calm wind becoming southeast around 5 mph in the afternoon.
Saturday Night
Mostly clear, with a low around 75. South wind 5 to 10 mph.
Sunday
Sunny, with a high near 97. Calm wind becoming south southeast around 5 mph in the morning.
Sunday Night
Mostly clear, with a low around 75.
Monday
Mostly sunny, with a high near 97.
Monday Night
Mostly clear, with a low around 75.
Tuesday
Mostly sunny, with a high near 98.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
3 Miles SSE San Marcos TX
 29.83°N 97.91°W (Elev. 620 ft)
Last Update:
6:42 am CDT Aug 26, 2026
Forecast Valid:
10am CDT Aug 26, 2026-6pm CDT Sep 1, 2026
 
Forecast Discussion
 
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Additional Resources

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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