Fire weather watches and red flag warnings, are issued when a weather event, that could contribute to large and/or dangerous fires, is forecast to occur.
Of the three sides of the fire behavior triangle (fuels, weather and topography), weather is the most variable and least predictable. Changes in weather can lead to unexpected fire behavior and result in danger to life and property, whether the fire is the result of a carefully planned prescribed fire or a wildfire.
A Fire Weather Watch or Red Flag Warning is issued by fire-weather forecasters to call attention to limited weather conditions of particular importance that may result in extreme burning conditions. It is issued when it is an on-going event or the fire weather forecaster has a high degree of confidence that Red Flag criteria will occur within 24 hours of issuance. Red Flag criteria occurs whenever a geographical area has been in a dry spell for a week or two, or for a shorter period , if before spring green-up or after fall color, and the National Fire Danger Rating System (NFDRS) is high to extreme and the following forecast weather parameters are forecasted to be met:
The image presented above highlights NWS offices with current Fire Weather Watches or Red Flag Warnings. Though the entire forecast office area is highlighted, the area of the Watch or Warning may be much smaller.