FFMC – Fine Fuel Moisture Code
Represents the moisture content in the surface litter and other cured fine fuels in a forest stand. The scale ranges from 0 to 99.
0-75 Difficult for ignition
75-80 Moderately difficult ignition
80-85 Moderately easy ignition
85-90 Easy ignition
91+ Very easy ignition
DMC – Duff Moisture Code
Represents the moisture content of loosely compacted, decomposing organic matter 5 to 10 cm deep.
0-20 Easy control
20-40 Easy to moderate control
41-70 Moderate to high difficulty of control
71+ High difficulty of control
DC – Drought Code
Represents the moisture content of slow drying fuels such as deep compact duff layers or concentrations of large downed wood.
0-120 Very easy mop up
121-200 Easy mop up
201-350 Effort required in mop up
351-500 Deep burning fire
501+ Very deep burning fuel
ISI – Initial Spread Index
Represents the initial spread rate of a fire arrived at by a combination of wind speed and fine fuel moisture content. The index doubles for every 15km/h increase of wind speed.
0-4 Spread rate generally slow at ignition
5-8 Moderate spread rates
9-12 High spread rates
13+ Very high spread rates
BUI – Buildup Index
Represents the amount of fuel available to the fire. Arrived at by combining the duff moisture and the drought codes. The basic assumption is that when the moisture content is low the greater the amount of available fuel.
0-40 Fire danger generally low
41-70 Fire danger generally moderate
71-120 Fire danger generally high
121+ Fire danger extreme
FWI – Fire Weather Index
This index combines the BUI (available fuel) and the ISI (rate of spread) to give an indication of fire behaviour.
0-7 Low Vigour Fire
7-14 Surface Fire
14-20 Candling and torching
20-30 Crown fire potential
DGR – Danger Class (FIRE DANGER)