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

81°F

27°C

Humidity 72%
Wind Speed S 9 mph
Barometer 29.98 in (1014.3 mb)
Dewpoint 71°F (22°C)
Visibility 10.00 mi
Heat Index85°F (29°C)
Last update 19 Jul 10:56 pm CDT
Extended Forecast for

San Marcos TX

  • Tonight

    Tonight: Partly cloudy, with a low around 73. South wind around 5 mph.

    Low: 73 °F

    Partly Cloudy

  • Monday

    Monday: Sunny, with a high near 95. Heat index values as high as 101. South southwest wind around 5 mph.

    High: 95 °F

    Sunny

  • Monday Night

    Monday Night: Clear, with a low around 70. South wind around 5 mph becoming calm after midnight.

    Low: 70 °F

    Clear

  • Tuesday

    Tuesday: Sunny, with a high near 97. Heat index values as high as 101. Calm wind becoming south around 5 mph in the afternoon.

    High: 97 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 75. Calm wind becoming south southwest around 5 mph after midnight.

    Low: 75 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny and hot, with a high near 99. West southwest wind around 5 mph becoming east southeast in the afternoon.

    High: 99 °F

    Hot

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 78. Southeast wind around 5 mph becoming calm in the evening.

    Low: 78 °F

    Mostly Clear

  • Thursday

    Thursday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 97. West wind around 5 mph becoming east southeast in the afternoon.

    High: 97 °F

    Sunny then
    Slight Chance
    T-storms

  • Thursday Night

    Thursday Night: A 20 percent chance of showers. Mostly clear, with a low around 77. East wind around 5 mph becoming south after midnight.

    Low: 77 °F

    Slight Chance
    Showers

Detailed Forecast

Tonight
Partly cloudy, with a low around 73. South wind around 5 mph.
Monday
Sunny, with a high near 95. Heat index values as high as 101. South southwest wind around 5 mph.
Monday Night
Clear, with a low around 70. South wind around 5 mph becoming calm after midnight.
Tuesday
Sunny, with a high near 97. Heat index values as high as 101. Calm wind becoming south around 5 mph in the afternoon.
Tuesday Night
Mostly clear, with a low around 75. Calm wind becoming south southwest around 5 mph after midnight.
Wednesday
Sunny and hot, with a high near 99. West southwest wind around 5 mph becoming east southeast in the afternoon.
Wednesday Night
Mostly clear, with a low around 78. Southeast wind around 5 mph becoming calm in the evening.
Thursday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 97. West wind around 5 mph becoming east southeast in the afternoon.
Thursday Night
A 20 percent chance of showers. Mostly clear, with a low around 77. East wind around 5 mph becoming south after midnight.
Friday
Sunny, with a high near 96.
Friday Night
Mostly clear, with a low around 76.
Saturday
Mostly sunny, with a high near 96.
Saturday Night
Mostly clear, with a low around 76.
Sunday
Mostly sunny, with a high near 95.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
San Marcos TX
 29.9°N 97.91°W (Elev. 640 ft)
Last Update:
11:32 pm CDT Jul 19, 2026
Forecast Valid:
11pm CDT Jul 19, 2026-6pm CDT Jul 26, 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