National Wildfire Coordinating Group

Interpreting Expected Surface Fire Behavior

Once estimates of Rate of Spread and Flame Length have been obtained, use these classifications to evaluate the level of concern they generate.

Fire Behavior Class Rate of Spread (ch/hr) Flame Length (ft) Tactical Interpretation
Very Low 0-2 0-1 Direct, Hand
Low 2-5 1-4 Direct, Hand
Moderate 5-20 4-8 Direct, Equip
High 20-50 8-12 Indirect
Very High 50-150 12-25 Indirect
Extreme 150+ 25+ Indirect

Surface Fire Behavior Characteristics Chart provides means for classifying and comparing individual fire events using spread rate and flame length (Fireline Intensity) or Heat per Unit Area.


PRINT FBFRG Interpreting Expected Surface Fire Behavior


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