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

67°F

19°C

Humidity 97%
Wind Speed SW 6 mph
Barometer 29.87 in (1010.9 mb)
Dewpoint 66°F (19°C)
Visibility 10.00 mi
Last update 22 May 2:56 am 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

  • Overnight

    Overnight: A 20 percent chance of showers and thunderstorms before 4am. Cloudy, with a low around 68. East wind around 5 mph becoming west.

    Low: 68 °F

    Slight Chance
    T-storms

  • Friday

    Friday: A 20 percent chance of showers and thunderstorms after 1pm. Cloudy, then gradually becoming mostly sunny, with a high near 86. Calm wind becoming south around 5 mph in the afternoon.

    High: 86 °F

    Partly Sunny
    then Slight
    Chance
    T-storms

  • Friday Night

    Friday Night: A 20 percent chance of showers and thunderstorms after 4am. Partly cloudy, with a low around 71. South southeast wind around 5 mph.

    Low: 71 °F

    Partly Cloudy
    then 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 around 5 mph in the afternoon. Chance of precipitation is 80%.

    High: 82 °F

    Chance
    T-storms then
    T-storms

  • Saturday Night

    Saturday Night: Showers likely and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 67. East wind around 5 mph becoming calm in the evening. Chance of precipitation is 60%.

    Low: 67 °F

    Showers
    Likely

  • Sunday

    Sunday: A 40 percent chance of showers and thunderstorms, mainly after 1pm. 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: Partly cloudy, with a low around 68. East northeast wind around 5 mph becoming calm in the evening.

    Low: 68 °F

    Partly Cloudy

  • Memorial Day

    Memorial Day: A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 85. North wind around 5 mph becoming east in the afternoon.

    High: 85 °F

    Mostly Sunny
    then Slight
    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

Detailed Forecast

Overnight
A 20 percent chance of showers and thunderstorms before 4am. Cloudy, with a low around 68. East wind around 5 mph becoming west.
Friday
A 20 percent chance of showers and thunderstorms after 1pm. Cloudy, then gradually becoming mostly sunny, with a high near 86. Calm wind becoming south around 5 mph in the afternoon.
Friday Night
A 20 percent chance of showers and thunderstorms after 4am. Partly cloudy, with a low around 71. South southeast wind around 5 mph.
Saturday
A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1pm. High near 82. Calm wind becoming south around 5 mph in the afternoon. Chance of precipitation is 80%.
Saturday Night
Showers likely and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 67. East wind around 5 mph becoming calm in the evening. Chance of precipitation is 60%.
Sunday
A 40 percent chance of showers and thunderstorms, mainly after 1pm. Mostly sunny, with a high near 82. Calm wind becoming northeast around 5 mph in the afternoon.
Sunday Night
Partly cloudy, with a low around 68. East northeast wind around 5 mph becoming calm in the evening.
Memorial Day
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 85. North wind around 5 mph becoming east 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.
Tuesday Night
Showers and thunderstorms likely. Mostly cloudy, with a low around 72. Chance of precipitation is 60%.
Wednesday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 85. Chance of precipitation is 70%.
Wednesday Night
A 40 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.
Basemap Options
Click map to change the forecast location
Loading map...
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 am CDT May 22, 2026
Forecast Valid:
3am CDT May 22, 2026-6pm CDT May 28, 2026
 
Forecast Discussion
 
Get as KML Get as XML

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