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

85°F

29°C

Humidity 65%
Wind Speed S 9 mph
Barometer 29.85 in (1010.1 mb)
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Heat Index91°F (33°C)
Last update 22 May 2:56 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 30 percent chance of showers and thunderstorms, mainly after 4pm. Mostly sunny, with a high near 84. South wind around 5 mph.

    High: 84 °F

    Chance
    T-storms

  • Tonight

    Tonight: A 30 percent chance of showers and thunderstorms, mainly before 7pm. Mostly cloudy, with a low around 70. South southeast wind around 5 mph.

    Low: 70 °F

    Chance
    T-storms then
    Mostly Cloudy

  • Saturday

    Saturday: Showers and thunderstorms likely, mainly after 1pm. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 82. Calm wind becoming south around 5 mph in the morning. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 82 °F

    Slight Chance
    T-storms then
    Heavy Rain

  • Saturday Night

    Saturday Night: A 40 percent chance of showers and thunderstorms, mainly after 4am. Mostly cloudy, with a low around 68. North northeast wind around 5 mph becoming calm in the evening.

    Low: 68 °F

    Chance
    T-storms then
    Chance
    Showers

  • Sunday

    Sunday: A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 82. Calm wind becoming northeast around 5 mph in the afternoon.

    High: 82 °F

    Chance
    T-storms

  • Sunday Night

    Sunday Night: A 20 percent chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 68. East northeast wind around 5 mph becoming calm in the evening.

    Low: 68 °F

    Slight Chance
    T-storms

  • Memorial Day

    Memorial Day: A 30 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 84. Calm wind becoming east northeast around 5 mph in the afternoon.

    High: 84 °F

    Mostly Sunny
    then Chance
    T-storms

  • Monday Night

    Monday Night: Mostly clear, with a low around 69. East wind around 5 mph becoming calm in the evening.

    Low: 69 °F

    Mostly Clear

  • Tuesday

    Tuesday: A 40 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 86. Calm wind becoming southeast around 5 mph in the afternoon.

    High: 86 °F

    Mostly Sunny
    then Chance
    T-storms

Detailed Forecast

This Afternoon
A 30 percent chance of showers and thunderstorms, mainly after 4pm. Mostly sunny, with a high near 84. South wind around 5 mph.
Tonight
A 30 percent chance of showers and thunderstorms, mainly before 7pm. Mostly cloudy, with a low around 70. South southeast wind around 5 mph.
Saturday
Showers and thunderstorms likely, mainly after 1pm. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 82. Calm wind becoming south around 5 mph in the morning. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Saturday Night
A 40 percent chance of showers and thunderstorms, mainly after 4am. Mostly cloudy, with a low around 68. North northeast wind around 5 mph becoming calm in the evening.
Sunday
A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 82. Calm wind becoming northeast around 5 mph in the afternoon.
Sunday Night
A 20 percent chance of showers and thunderstorms 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 after 1pm. Mostly sunny, with a high near 84. Calm wind becoming east northeast around 5 mph in the afternoon.
Monday Night
Mostly clear, with a low around 69. East wind around 5 mph becoming calm in the evening.
Tuesday
A 40 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 86. Calm wind becoming southeast around 5 mph in the afternoon.
Tuesday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 71. Chance of precipitation is 70%.
Wednesday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 84. Chance of precipitation is 70%.
Wednesday Night
A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 71.
Thursday
A 30 percent chance of showers and thunderstorms. Partly sunny, with a high near 87.
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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:
2:46 pm CDT May 22, 2026
Forecast Valid:
3pm CDT May 22, 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