Definitions for "Red flag warning"
A National Weather Service product that is issued when red flag conditions (i.e., a critical fire weather situation) are expected.
Awarning that is issued to alert forecasters of an ongoing or imminent critical fire weather pattern. When such a warning is issued there are many factors that can affect the warning. Some of the factors are the size of the fire and the winds around the fire. These warning are issued to inform the public about a possible threat and to keep people out of harms way.
a warning to the fire fighting community that if there is a fire, the weather conditions can be expected to cause erratic fire behavior