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.

Ranges

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.

Ranges

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.

Ranges

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.

Ranges

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.

Ranges

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.

Ranges

0-7             Low Vigour Fire

7-14           Surface Fire

14-20         Candling and torching

20-30         Crown fire potential

30+             Blowup

DGR – Danger Class (FIRE DANGER)

Ranges

1               Nil

2               Low

3               Moderate

4               High

5               Extreme