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

Risks of Severe Thunderstorms and Excessive Rainfall; Fire Weather Concerns and Record Warmth

Severe thunderstorms and flash flooding risks increase across the center of the nation today. Meanwhile, ongoing thunderstorms and flash flooding will linger along the Gulf Coast states through the evening. The Great Basin and Intermountain West, warm temperatures and dry fuels with dry lightning may enhance fire weather potential. In addition, across interior Alaska, Red Flag Warning are posted. Read More >

Current conditions at

San Marcos, San Marcos Municipal Airport (KHYI)

Lat: 29.89°NLon: 97.86°WElev: 597ft.

Light Rain Haze

73°F

23°C

Humidity 96%
Wind Speed SW 5 mph
Barometer 29.93 in (1012.6 mb)
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Last update 20 Jun 5:56 am CDT
Extended Forecast for

San Marcos TX

  • Today

    Today: A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 90. Heat index values as high as 100. South southeast wind 5 to 10 mph.

    High: 90 °F

    Chance
    T-storms

  • Tonight

    Tonight: A 20 percent chance of showers after 4am. Mostly cloudy, with a low around 77. South southeast wind 5 to 10 mph.

    Low: 77 °F

    Mostly Cloudy
    then Slight
    Chance
    Showers

  • Sunday

    Sunday: A 20 percent chance of showers and thunderstorms before 10am. Mostly sunny, with a high near 93. Heat index values as high as 103. South wind 5 to 15 mph, with gusts as high as 25 mph.

    High: 93 °F

    Slight Chance
    T-storms then
    Mostly Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 77. South wind around 15 mph, with gusts as high as 25 mph.

    Low: 77 °F

    Partly Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 95. South wind 10 to 15 mph, with gusts as high as 25 mph.

    High: 95 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 77. South southeast wind 10 to 15 mph, with gusts as high as 25 mph.

    Low: 77 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 95. South wind 5 to 10 mph.

    High: 95 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 76. South southeast wind 5 to 10 mph, with gusts as high as 20 mph.

    Low: 76 °F

    Mostly Clear

  • Wednesday

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

    High: 95 °F

    Mostly Sunny

Detailed Forecast

Today
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 90. Heat index values as high as 100. South southeast wind 5 to 10 mph.
Tonight
A 20 percent chance of showers after 4am. Mostly cloudy, with a low around 77. South southeast wind 5 to 10 mph.
Sunday
A 20 percent chance of showers and thunderstorms before 10am. Mostly sunny, with a high near 93. Heat index values as high as 103. South wind 5 to 15 mph, with gusts as high as 25 mph.
Sunday Night
Partly cloudy, with a low around 77. South wind around 15 mph, with gusts as high as 25 mph.
Monday
Mostly sunny, with a high near 95. South wind 10 to 15 mph, with gusts as high as 25 mph.
Monday Night
Partly cloudy, with a low around 77. South southeast wind 10 to 15 mph, with gusts as high as 25 mph.
Tuesday
Mostly sunny, with a high near 95. South wind 5 to 10 mph.
Tuesday Night
Mostly clear, with a low around 76. South southeast wind 5 to 10 mph, with gusts as high as 20 mph.
Wednesday
Mostly sunny, with a high near 95. South wind 5 to 10 mph.
Wednesday Night
Partly cloudy, with a low around 74.
Thursday
Mostly sunny, with a high near 95.
Thursday Night
Mostly clear, with a low around 75.
Friday
Mostly sunny, with a high near 95.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
San Marcos TX
 29.88°N 97.94°W (Elev. 577 ft)
Last Update:
5:32 am CDT Jun 20, 2026
Forecast Valid:
6am CDT Jun 20, 2026-6pm CDT Jun 26, 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