Facing frigid wind chill values of 12 to 20 degrees across the region, Houston and much of Southeast Texas are under a cold weather advisory until 6 p.m. Tuesday, the National Weather Service said. Given that the coldest temperatures of this Texas freeze are expected before dawn on Wednesday, with some wind chill values possibly in single digits, the weather service also put the Houston metro area under an extreme cold watch starting at 6 p.m. Tuesday through 9 a.m. Wednesday. For a cold weather advisory or an extreme cold watch to be issued, dangerously cold wind chills below 10 degrees are possible, particularly where snow has fallen the most. Forecasters warned that prolonged exposure to weather producing low wind chill values can lead to hypothermia. https://www.houstonchronicle.com/news/houston-weather/forecast/article/freeze-cold-weather-advisory-snow-reports-20046549.php