A burst of arctic air settles into the region later this week. While dangerous cold was felt for many Tuesday morning, more sustained, frigid temperatures arrive on Thursday night and continue through Sunday morning. According to the National Weather Service, air temperatures will drop below zero for several hours, and wind chill values as low as 30 degrees below are possible, especially on Friday morning. Frostbite and hypothermia can occur in those conditions in as little as 15 minutes.