Understanding cold weather alertsExtreme cold warning: Take Action! An extreme cold warning is issued when dangerously cold air temperatures or wind chill values are expected or occurring. If you are in an area with an extreme cold warning, avoid going outside. An extreme cold watch is issued when dangerously cold air temperatures or wind chill values are possible. A cold weather advisory is issued when seasonably cold air temperatures or wind chill values, but not extremely cold values, are expected or occurring.