DALLAS — Hundreds of flights have been canceled in Texas, where frigid temperatures have left runways — and roads — dangerously icy.

The National Weather Service issued a winter storm warning for the Houston area on Tuesday and is warning mariners of gale-force winds along the Texas coast. Sleet and freezing rain are forecast for parts of the state.

AUSTIN-BERGSTROM FLIGHT INFO | SAN ANTONIO INTERNATIONAL FLIGHT INFO

Flights into Houston, San Antonio and elsewhere have been canceled. Houston is enduring 21 degrees and San Antonio stands at 30 degrees.

Police in Austin say highways in the capital are iced over and several counties opened emergency operation centers to coordinate emergency response.

The cold front also brought snow to parts of North Texas, where the wind chill pushed temperatures into the single digits.