What is the fuel moisture at which fire will not spread called?

The term that refers to the fuel moisture at which fire will not spread is known as the moisture of extinction. This is the critical moisture level in the fuel that determines if a fire can continue to propagate. When the moisture content of the fuel reaches this level, it effectively limits the fire's ability to sustain combustion, therefore extinguishing or greatly inhibiting its spread.

Understanding this concept is vital for wildland fire behavior analysis, as it helps in evaluating fire suppression strategies and predicting fire activity in different fuel types and conditions. Numerous factors influence fuel moisture, including environmental conditions such as temperature, relative humidity, and precipitation, making it a key consideration in fire management and safety assessments.