FFMC (0-99) - The Fine Fuel Moisture Code (FFMC) represents the moisture content of small woody debris. It, along with the DMC, are indicators of the ease of ignition and flammability of the fine fuels. “How easy is it to start a fire?”
Wind Speed - Wind dries fuels by moving moisture laden air away from the fuels and replacing it with drier air which can then draw up more moisture, thereby continually drying the fuels. Wind speed influences the rate of fire spread. Burning embers can also be transported by wind and blown onto new fuels ahead of a fire.
ISI (0-185) - The Initial Spread Index (ISI) is a computed index derived from the FFMC and wind. When combined with the DMC, fuel type, and slope we get a measure of the potential Rate of Spread. “How far and fast a fire will it go once started?”
DMC (0-462) - The Drought Moisture Code (DMC) represents the moisture content of medium woody debris and moderate depth sub-surface fuels.
DC (0-1200) - The Drought Code (DC) represents the moisture content of large logs and deep sub-surface fuels and is an indicator of the seasonal drought effect.
BUI (0-437) - The Build Up Index (BUI) is a computed index derived from the DMC and the DC. All three indices, along with the spread class and fuel type, represents a fires difficulty of control. “If a fire starts, how much effort will it take to control and put that fire out?”
FWI (0-210) - The Fire Weather Index (FWI) is a model that is used to evaluate fire behaviour in terms of fuel moisture and weather conditions. The raw inputs are temperature, relative humidity, wind, and rain.
DGR (I-V) - The Fire Danger Class (DGR) is a numeric representation of the potential fire load. It’s used primarily as an administrative aid to evaluate the potential costs plus damage that may results from fires. The ministry has guidelines on what work precautions and restriction should be implemented given the different regions. It’s derived from the FWI and BUI and is only used in British Columbia.
There are five values: Very Low (I), Low (II), Moderate (III), High (IV), and Extreme (V).