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.

Mostly Cloudy with Haze

80°F

27°C

Humidity 69%
Wind Speed SE 7 mph
Barometer 29.90 in (1011.7 mb)
Dewpoint 69°F (21°C)
Visibility 4.00 mi
Heat Index83°F (28°C)
Last update 21 May 3:56 pm CDT
Extended Forecast for

San Marcos TX

Flood Watch May 22, 07:00pm until May 25, 07:00pm
Click here for hazard details and duration
Flood Watch

  • This Afternoon

    This Afternoon: A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 80. South southeast wind around 5 mph.

    High: 80 °F

    Chance
    T-storms

  • Tonight

    Tonight: A 30 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 68. Southeast wind around 5 mph becoming calm.

    Low: 68 °F

    Chance
    T-storms then
    Chance
    Showers

  • Friday

    Friday: A slight chance of showers and thunderstorms before 10am, then a slight chance of showers and thunderstorms after 4pm. Mostly sunny, with a high near 86. Calm wind becoming south around 5 mph in the afternoon. Chance of precipitation is 20%.

    High: 86 °F

    Slight Chance
    T-storms

  • Friday Night

    Friday Night: A 20 percent chance of showers and thunderstorms, mainly between 10pm and 1am. Increasing clouds, with a low around 71. Southeast wind around 5 mph becoming calm in the evening.

    Low: 71 °F

    Slight Chance
    T-storms

  • Saturday

    Saturday: A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1pm. High near 82. Calm wind becoming south southeast around 5 mph in the afternoon. Chance of precipitation is 90%.

    High: 82 °F

    Chance
    T-storms then
    T-storms

  • Saturday Night

    Saturday Night: Showers likely and possibly a thunderstorm before 10pm, then showers likely between 10pm and 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 68. Southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 70%.

    Low: 68 °F

    Showers
    Likely

  • Sunday

    Sunday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Partly sunny, with a high near 83. Calm wind becoming east northeast around 5 mph in the afternoon. Chance of precipitation is 60%.

    High: 83 °F

    Chance
    T-storms then
    Showers
    Likely

  • Sunday Night

    Sunday Night: A 30 percent chance of showers and thunderstorms, mainly before 1am. Partly cloudy, with a low around 68. East northeast wind around 5 mph becoming calm in the evening.

    Low: 68 °F

    Chance
    T-storms

  • Memorial Day

    Memorial Day: A 30 percent chance of showers and thunderstorms, mainly after 1pm. Mostly sunny, with a high near 85. Calm wind becoming east northeast around 5 mph in the morning.

    High: 85 °F

    Chance
    T-storms

Detailed Forecast

This Afternoon
A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 80. South southeast wind around 5 mph.
Tonight
A 30 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 68. Southeast wind around 5 mph becoming calm.
Friday
A slight chance of showers and thunderstorms before 10am, then a slight chance of showers and thunderstorms after 4pm. Mostly sunny, with a high near 86. Calm wind becoming south around 5 mph in the afternoon. Chance of precipitation is 20%.
Friday Night
A 20 percent chance of showers and thunderstorms, mainly between 10pm and 1am. Increasing clouds, with a low around 71. Southeast wind around 5 mph becoming calm in the evening.
Saturday
A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1pm. High near 82. Calm wind becoming south southeast around 5 mph in the afternoon. Chance of precipitation is 90%.
Saturday Night
Showers likely and possibly a thunderstorm before 10pm, then showers likely between 10pm and 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 68. Southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 70%.
Sunday
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Partly sunny, with a high near 83. Calm wind becoming east northeast around 5 mph in the afternoon. Chance of precipitation is 60%.
Sunday Night
A 30 percent chance of showers and thunderstorms, mainly before 1am. Partly cloudy, with a low around 68. East northeast wind around 5 mph becoming calm in the evening.
Memorial Day
A 30 percent chance of showers and thunderstorms, mainly after 1pm. Mostly sunny, with a high near 85. Calm wind becoming east northeast around 5 mph in the morning.
Monday Night
Partly cloudy, with a low around 70.
Tuesday
A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 86.
Tuesday Night
Showers and thunderstorms likely. Mostly cloudy, with a low around 71. Chance of precipitation is 60%.
Wednesday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 83. Chance of precipitation is 70%.
Wednesday Night
A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 71.
Thursday
A chance of showers and thunderstorms. Partly sunny, with a high near 86.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
San Marcos TX
 29.9°N 97.91°W (Elev. 640 ft)
Last Update:
2:46 pm CDT May 21, 2026
Forecast Valid:
4pm CDT May 21, 2026-6pm CDT May 28, 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