Red flag warning

[1] These include drought conditions or a dry season, very low humidity, high or erratic winds, and the possibility of lightning.

Outdoor burning bans may also be proclaimed by local law and fire agencies based on red flag warnings, for both the general public and land management officials.

A fire weather warning gives extra guidance to land management officials to refrain from controlled burns.

In October 2019, the National Weather Service introduced a variant to denote even more dangerous conditions: extreme red flag warning.

Analogous to the particularly dangerous situation (PDS) wording on a high-end severe weather warning or watch, this means that conditions for fire growth and behavior are extremely dangerous due to a combination of strong winds, very low humidity, long duration, and very dry fuels.