The Fire Danger Index, commonly referred to as the FDI, is a rating system that provides an indication as to the fire risk for a specific area on a specific day. If the expected environmental factors are know for the coming period, the FDI can be forecast. Likewise the FDI can be calculated for the real-time (i.e. present time) conditions.
While handy as an indication for activities that are fire related (camp cooking, prescribed burning, machinery operation, etc.), it can sometimes be misleading, as it is not foolproof.
The environmental factors used to calculate the FDI are :
a Temperature : Readings taken in ° C
b) Relative humidity : The percentage of moisture in the air. The less moisture, the higher the value. 100 % RH = mist / rain / fog
c) Wind speed : The stronger the wind, the greater the fire risk
d) Previous rain : This is tabulated according to when last and how much fell. Expected rainfall is not considered, even if there is certainty it is going occur. This however is countered by the expected Relative Humidity.
All these factors are allocated values, and the total is allocated to a colour coded group.
Blue : 0 – 20 : SAFE : Cold and wet
Green : 21 – 45 : MODERATE : Low fire risk. Care to be taken for burning operations
Yellow : 46 – 60 : DANGEROUS : Caution advised
Orange : 61 – 75 : VERY DANGEROUS : Teams kept on stand by. No open flames.
Red : 81 – 100 : EXTREME. Warnings presented on radio and TV forecasts.