A new set of nationally agreed fire danger ratings (FDR) has now been adopted by all states across Australia recognising the increasing severity of fire risk and its potential impact on communities. The FDR is an assessment of the potential fire behaviour, the difficulty in supressing a fire and the potential impact on the community should a fire break out.
There are now six levels of risk rating ranging from the most severe:
- Very High
The risk to a particular area is determined daily by the Bureau of Meteorology (BOM). The BOM produces a fire danger index (FDI) forecast each day during the bushfire season, considering the forecasted weather conditions and typography of the area that day. They also consider whether there are any existing fires in the area, the dryness of the fuel, likelihood of lightning and other factors.
A catastrophic FDR means that should there be a bush fire, the consequences would be devastating because it will be aggressive, unpredictable, fast moving and uncontrollable. Ember attack is within the range of 20km. In the event of a catastrophic rating being declared, all residents should be prepared to leave for the safety of a township or shelter and defending their property is not a safe option.
In Sydney, the severe FDR is most commonly used. This indicates that fires are likely to be uncontrollable and fast moving, with embers spreading to within 4km of the main fire. Whilst it is advisable to leave the home, those staying behind to defend should do so if they are sufficiently capable and the property is well prepared.