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.

Overcast

80°F

27°C

Humidity 90%
Wind Speed SE 10 mph
Barometer 29.85 in (1010.0 mb)
Dewpoint 77°F (25°C)
Visibility 10.00 mi
Heat Index86°F (30°C)
Last update 17 May 11:56 pm CDT
Extended Forecast for

San Marcos TX

  • Overnight

    Overnight: A 20 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 76. South southeast wind 5 to 10 mph.

    Low: 76 °F

    Slight Chance
    T-storms

  • Sunday

    Sunday: Widespread haze before 11am. Cloudy, then gradually becoming mostly sunny, with a high near 96. Heat index values as high as 104. South wind 10 to 15 mph, with gusts as high as 25 mph.

    High: 96 °F

    Haze then
    Partly Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 76. South southeast wind 10 to 15 mph, with gusts as high as 25 mph.

    Low: 76 °F

    Mostly Cloudy

  • Monday

    Monday: A 20 percent chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 97. Heat index values as high as 106. South wind 10 to 15 mph, with gusts as high as 30 mph.

    High: 97 °F

    Mostly Cloudy
    then Slight
    Chance
    T-storms

  • Monday Night

    Monday Night: A 20 percent chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 72. South southeast wind 5 to 15 mph, with gusts as high as 25 mph.

    Low: 72 °F

    Partly Cloudy
    then Slight
    Chance
    T-storms

  • Tuesday

    Tuesday: Sunny and hot, with a high near 99. South wind around 5 mph becoming north in the afternoon.

    High: 99 °F

    Hot

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 67. Northeast wind around 5 mph.

    Low: 67 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 95. East northeast wind 5 to 10 mph.

    High: 95 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 64. East wind 5 to 10 mph.

    Low: 64 °F

    Mostly Cloudy

Detailed Forecast

Overnight
A 20 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 76. South southeast wind 5 to 10 mph.
Sunday
Widespread haze before 11am. Cloudy, then gradually becoming mostly sunny, with a high near 96. Heat index values as high as 104. South wind 10 to 15 mph, with gusts as high as 25 mph.
Sunday Night
Mostly cloudy, with a low around 76. South southeast wind 10 to 15 mph, with gusts as high as 25 mph.
Monday
A 20 percent chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 97. Heat index values as high as 106. South wind 10 to 15 mph, with gusts as high as 30 mph.
Monday Night
A 20 percent chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 72. South southeast wind 5 to 15 mph, with gusts as high as 25 mph.
Tuesday
Sunny and hot, with a high near 99. South wind around 5 mph becoming north in the afternoon.
Tuesday Night
Partly cloudy, with a low around 67. Northeast wind around 5 mph.
Wednesday
Mostly sunny, with a high near 95. East northeast wind 5 to 10 mph.
Wednesday Night
Mostly cloudy, with a low around 64. East wind 5 to 10 mph.
Thursday
Mostly sunny, with a high near 94.
Thursday Night
Partly cloudy, with a low around 63.
Friday
Sunny, with a high near 96.
Friday Night
Partly cloudy, with a low around 67.
Saturday
Mostly sunny, with a high near 97.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
San Marcos TX
 29.88°N 97.91°W (Elev. 597 ft)
Last Update:
11:51 pm CDT May 17, 2025
Forecast Valid:
12am CDT May 18, 2025-6pm CDT May 24, 2025
 
Forecast Discussion
 
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Additional Resources

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation