Spread Component (SC) is a rating of the forward rate of spread of a head fire. It integrates the effects of wind, slope, fuel bed characteristics, and fuel particle properties. Daily variations occur due to changes in wind and moisture content in live fuels, as well as in the Moisture 1H, Moisture 10H, and Moisture 100H dead fuel time lag classes. Higher SC values correspond to faster spread rates.
The closest Canadian equivalent is the Initial Spread Index (ISI).