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

44°F

7°C

Humidity 28%
Wind Speed SW 3 mph
Barometer 30.25 in (1024.3 mb)
Dewpoint 13°F (-11°C)
Visibility 10.00 mi
Last update 18 Jan 9:56 pm CST
Extended Forecast for

3 Miles NNW San Marcos Municipal Airport TX

  • Tonight

    Tonight: Clear, with a low around 30. Southwest wind around 5 mph.

    Low: 30 °F

    Clear

  • M.L.King Day

    M.L.King Day: Sunny, with a high near 66. Light and variable wind becoming south southeast 5 to 10 mph in the afternoon.

    High: 66 °F

    Sunny

  • Monday Night

    Monday Night: Increasing clouds, with a low around 40. East southeast wind around 5 mph becoming north northeast after midnight.

    Low: 40 °F

    Increasing
    Clouds

  • Tuesday

    Tuesday: Cloudy, with a high near 57. North northeast wind around 5 mph becoming east southeast in the afternoon.

    High: 57 °F

    Cloudy

  • Tuesday Night

    Tuesday Night: A 50 percent chance of showers.  Cloudy, with a low around 49. South southeast wind around 5 mph.

    Low: 49 °F

    Chance
    Showers

  • Wednesday

    Wednesday: A 40 percent chance of showers, mainly before noon.  Mostly cloudy, with a high near 65. South southeast wind around 5 mph.

    High: 65 °F

    Chance
    Showers

  • Wednesday Night

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

    Low: 50 °F

    Mostly Cloudy

  • Thursday

    Thursday: Partly sunny, with a high near 69. North wind around 5 mph becoming east in the afternoon.

    High: 69 °F

    Partly Sunny

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 49. East wind around 5 mph becoming south southeast after midnight.

    Low: 49 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Clear, with a low around 30. Southwest wind around 5 mph.
M.L.King Day
Sunny, with a high near 66. Light and variable wind becoming south southeast 5 to 10 mph in the afternoon.
Monday Night
Increasing clouds, with a low around 40. East southeast wind around 5 mph becoming north northeast after midnight.
Tuesday
Cloudy, with a high near 57. North northeast wind around 5 mph becoming east southeast in the afternoon.
Tuesday Night
A 50 percent chance of showers. Cloudy, with a low around 49. South southeast wind around 5 mph.
Wednesday
A 40 percent chance of showers, mainly before noon. Mostly cloudy, with a high near 65. South southeast wind around 5 mph.
Wednesday Night
Mostly cloudy, with a low around 50. East southeast wind around 5 mph becoming north after midnight.
Thursday
Partly sunny, with a high near 69. North wind around 5 mph becoming east in the afternoon.
Thursday Night
Mostly cloudy, with a low around 49. East wind around 5 mph becoming south southeast after midnight.
Friday
A 20 percent chance of showers after noon. Mostly cloudy, with a high near 69.
Friday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 37.
Saturday
A 40 percent chance of showers. Mostly cloudy, with a high near 46.
Saturday Night
Mostly cloudy, with a low around 29.
Sunday
A 20 percent chance of showers. Mostly cloudy, with a high near 42.
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ABOUT THIS FORECAST

 
Point Forecast:
3 Miles NNW San Marcos Municipal Airport TX
 29.95°N 97.89°W (Elev. 646 ft)
10:00 pm CST Jan 18, 2026
10pm 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