noun
spread of a fire; progress of a fire
Refers to how quickly or in what direction a fire spreads. Often used in news reports and firefighting contexts.
強風で火脚が速まり、消火活動が難航した。
The strong wind accelerated the spread of the fire, making firefighting efforts difficult.
火脚が弱まったため、延焼の危険は低くなった。
Because the fire's progress slowed, the risk of it spreading further decreased.
延焼 is a more formal term for the spread of fire, often used in official reports, while 火脚 focuses on the speed or manner of the fire's advance.
Compound of 火 (hi, 'fire') and 脚 (ashi, 'legs'), literally 'fire legs', metaphorically describing the movement and speed of a fire's spread.