Lake-effect Snow and Whiteout Conditions in the Great Lakes Region; Below-average Temperatures in the East

Heavy lake-effect and lake-enhanced snow will persist downwind of the Great Lakes and produce some whiteout conditions that could cause difficult travel conditions. A coastal low will produce moderate to heavy snow over parts of southern and eastern New England into the afternoon. Below average temperatures are expected across the eastern U.S., particularly with chilly morning temperatures. Read More >

Current conditions at

San Marcos, San Marcos Municipal Airport (KHYI)

Lat: 29.89°NLon: 97.86°WElev: 597ft.

Fair

47°F

8°C

Humidity 24%
Wind Speed S 3 mph
Barometer 30.24 in (1024.4 mb)
Dewpoint 12°F (-11°C)
Visibility 10.00 mi
Last update 18 Jan 8:56 pm CST
Extended Forecast for

San Marcos TX

  • Tonight

    Tonight: Clear, with a low around 31. West southwest wind around 5 mph.

    Low: 31 °F

    Clear

  • M.L.King Day

    M.L.King Day: Sunny, with a high near 65. Calm wind becoming southeast around 5 mph in the afternoon.

    High: 65 °F

    Sunny

  • Monday Night

    Monday Night: Increasing clouds, with a low around 43. Northeast wind 5 to 10 mph.

    Low: 43 °F

    Increasing
    Clouds

  • Tuesday

    Tuesday: Cloudy, with a high near 58. North northeast wind 5 to 10 mph becoming east southeast in the afternoon.

    High: 58 °F

    Cloudy

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers, mainly after midnight.  Cloudy, with a low around 51. Southeast wind around 5 mph.

    Low: 51 °F

    Chance
    Showers

  • Wednesday

    Wednesday: A 40 percent chance of showers, mainly before noon.  Mostly cloudy, with a high near 64. Southeast wind around 5 mph.

    High: 64 °F

    Chance
    Showers

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 50. East southeast wind 5 to 10 mph becoming north northeast after midnight.

    Low: 50 °F

    Mostly Cloudy

  • Thursday

    Thursday: Partly sunny, with a high near 63. North northeast wind around 5 mph.

    High: 63 °F

    Partly Sunny

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 46. Northeast wind around 5 mph becoming south southeast after midnight.

    Low: 46 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Clear, with a low around 31. West southwest wind around 5 mph.
M.L.King Day
Sunny, with a high near 65. Calm wind becoming southeast around 5 mph in the afternoon.
Monday Night
Increasing clouds, with a low around 43. Northeast wind 5 to 10 mph.
Tuesday
Cloudy, with a high near 58. North northeast wind 5 to 10 mph becoming east southeast in the afternoon.
Tuesday Night
A 30 percent chance of showers, mainly after midnight. Cloudy, with a low around 51. Southeast wind around 5 mph.
Wednesday
A 40 percent chance of showers, mainly before noon. Mostly cloudy, with a high near 64. Southeast wind around 5 mph.
Wednesday Night
Mostly cloudy, with a low around 50. East southeast wind 5 to 10 mph becoming north northeast after midnight.
Thursday
Partly sunny, with a high near 63. North northeast wind around 5 mph.
Thursday Night
Mostly cloudy, with a low around 46. Northeast wind around 5 mph becoming south southeast after midnight.
Friday
Partly sunny, with a high near 67.
Friday Night
A 20 percent chance of showers. Mostly cloudy, with a low around 52.
Saturday
A 20 percent chance of showers. Mostly cloudy, with a high near 66.
Saturday Night
A 20 percent chance of showers. Mostly cloudy, with a low around 40.
Sunday
Mostly cloudy, with a high near 53.
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ABOUT THIS FORECAST

 
Point Forecast:
San Marcos TX
 29.88°N 97.94°W (Elev. 577 ft)
5:46 pm CST Jan 18, 2026
9pm CST Jan 18, 2026-6pm CST Jan 25, 2026
 
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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