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.

Overcast

67°F

19°C

Humidity 93%
Wind Speed NE 10 mph
Barometer 30.07 in (1017.6 mb)
Dewpoint 65°F (18°C)
Visibility 10.00 mi
Last update 20 May 12:56 am CDT
Extended Forecast for

San Marcos TX

  • Overnight

    Overnight: A 50 percent chance of showers and thunderstorms. Cloudy, with a low around 69. East northeast wind around 5 mph. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    Low: 69 °F

    Chance
    T-storms

  • Wednesday

    Wednesday: A 20 percent chance of showers and thunderstorms after 4pm. Partly sunny, with a high near 83. East southeast wind around 5 mph.

    High: 83 °F

    Partly Sunny
    then Slight
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 4am. Mostly cloudy, with a low around 71. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.

    Low: 71 °F

    Chance
    T-storms then
    Showers
    Likely

  • Thursday

    Thursday: Showers and thunderstorms likely before 1pm, then showers likely and possibly a thunderstorm between 1pm and 4pm, then a chance of showers and thunderstorms after 4pm. Mostly cloudy, with a high near 81. North northeast wind around 5 mph becoming south in the morning. Chance of precipitation is 70%.

    High: 81 °F

    Showers
    Likely

  • Thursday Night

    Thursday Night: A 40 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 70. Southeast wind around 5 mph becoming calm in the evening.

    Low: 70 °F

    Chance
    T-storms then
    Chance
    Showers

  • Friday

    Friday: A 40 percent chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 86. South wind around 5 mph.

    High: 86 °F

    Mostly Cloudy
    then Chance
    T-storms

  • Friday Night

    Friday Night: A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 71. Southeast wind around 5 mph.

    Low: 71 °F

    Chance
    T-storms

  • Saturday

    Saturday: A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1pm. High near 83. South southeast wind around 5 mph. Chance of precipitation is 80%.

    High: 83 °F

    Chance
    T-storms then
    T-storms

  • Saturday Night

    Saturday Night: Showers and possibly a thunderstorm. Low around 69. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 80%.

    Low: 69 °F

    Showers

Detailed Forecast

Overnight
A 50 percent chance of showers and thunderstorms. Cloudy, with a low around 69. East northeast wind around 5 mph. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Wednesday
A 20 percent chance of showers and thunderstorms after 4pm. Partly sunny, with a high near 83. East southeast wind around 5 mph.
Wednesday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 4am. Mostly cloudy, with a low around 71. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.
Thursday
Showers and thunderstorms likely before 1pm, then showers likely and possibly a thunderstorm between 1pm and 4pm, then a chance of showers and thunderstorms after 4pm. Mostly cloudy, with a high near 81. North northeast wind around 5 mph becoming south in the morning. Chance of precipitation is 70%.
Thursday Night
A 40 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 70. Southeast wind around 5 mph becoming calm in the evening.
Friday
A 40 percent chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 86. South wind around 5 mph.
Friday Night
A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 71. Southeast wind around 5 mph.
Saturday
A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1pm. High near 83. South southeast wind around 5 mph. Chance of precipitation is 80%.
Saturday Night
Showers and possibly a thunderstorm. Low around 69. East southeast wind around 5 mph becoming calm in the evening. Chance of precipitation is 80%.
Sunday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 83. Chance of precipitation is 60%.
Sunday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 69.
Memorial Day
A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 85.
Monday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 70.
Tuesday
A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 85.
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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:
1:24 am CDT May 20, 2026
Forecast Valid:
1am CDT May 20, 2026-6pm CDT May 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