FOREST FIRE DANGER INDEX (FFDI)

The Forest Fire Danger Index (FFDI) was developed in the 1960s by CSIRO scientist A.G. McArthur to measure the degree of danger of fire in Australian forests. The index combines a record of dryness, based on rainfall and evaporation, with meteorological variables for windspeed, temperature and humidity.
A FFDI of between 12 and 25 on the index is considered a "high" degree of danger, while a day having a danger rating of over 50 is considered an "Severe" fire danger rating. Above this level in 2010 a distinction was made between Forest and Grassland fuels. For Forest fuels, an FDI over 75 is categorised as "Extreme" and over 100 as "Catastrophic" (In Victoria the alternate rating name of "Code Red" has been adopted). For Grassland Fuels the threshold FDI values for the Extreme and Catastrophic Ratings was increased to 100 and 150 respectively.



Category Forest Fire Danger Index Grassland Fire Danger Index
Catastrophic (Code Red) 100 + 150 +
Extreme 75 – 99 100 – 149
Severe 50 – 74 50 – 99
Very High 25 – 49 25 – 49
High 12 – 24 12 – 24
Low–Moderate 0 – 11 0 – 11