Fire Danger Ratings

Fire Danger Ratings

A new approach to defining Fire Danger Ratings has been developed nationally to provide improved information to calculate the risk faced from bushfires and minimise the chance of suffering property loss or injury by becoming better prepared.

The Fire Danger Rating is derived as a scale of Fire Danger Index likely to be experienced for the following day and provided to the fire authorities by the Bureau of Meteorology (BoM) late each afternoon. The BoM forecasters calculate Fire Danger Index by combining variables such as forecast temperature, relative humidity, wind speed and direction, vegetation type and available fuel volume, days since rain, level of ‘curing’ or dryness of vegetation fuel and other related factors. The figure resulting from the combination of these factors is based on bushfire science research and assists as an indicator of potential difficulty in controlling a fire should a bushfire start on that particular day.

You would have seen the signboards as depicted below of a graded scale from Low to Extreme, with the arrow pointed at the present level of risk. Each colour represents a range/scale of Fire Danger Index, (FDI). What is new as a result of these national discussions is the incorporation of a new state of alert “Catastrophic” which takes effect when the fire danger index (FDI) reaches and exceeds a figure of 100.

Fire Danger Ratings

The table below will help you understand what each rating means in reference to fire behaviour so that you can be aware of the actions you need to plan and initiate to protect yourself. As fire weather conditions become more severe, the likelihood of a fire truck and firefighters being available to assist you should a fire occur is going to be reduced as the fire authorities’ resources will be required in many areas at the same time.

For example: low to moderate:

Fire Danger Rating

Fire Danger Index

Fire Behaviour and Impact potential

Recommended Action

Catastrophic

100+

  • Fire will threaten without warning. It will be difficult to see, hear and breathe.
  • Fires may be uncontrollable and fast moving. A significant amount of burning embers will be blown around and spot fires will start, often many kilometres ahead of the main fire.
  • There is a strong likelihood that people unprepared may suffer serious, if not life threatening injury. Property in the path of the fire is likely to be destroyed.  Even well prepared homes may not survive as house building standards do not require a dwelling to be constructed to withstand fire in excess of a fire danger index of 100, and many will be ignited by spot fires caused by burning embers.
  • Expect wide scale power, telephone and water supply failure.
  • Do not expect a fire truck or firefighters to attend.
  • Ensure that your survival is the first priority in implementing your Bushfire Survival plan in these conditions.
  • For maximum probability of survival, leaving early in the day of catastrophic conditions is the best option.
  • It will not be safe to stay and defend even the best prepared property.
  • Stay well informed of the current fire situation throughout a day of catastrophic fire danger by remaining tuned to local media on a battery powered radio.

Extreme

75–99

  • Fire will threaten suddenly and it will be hot, windy and difficult to see, hear and breathe.
  • Fires will be very difficult to control and fast moving. Burning embers will be blown around and start spot fires.
  • There is a potential for property in the path of the fire, or impacted by ember attack to be lost, and people may suffer serious if not life threatening injury.
  • Only very well prepared homes will be likely to offer any degree of safety.
  • Expect power, telephone and water supply failure.
  • Do not expect a fire truck or firefighters to attend. 
  • Ensure that your survival is the first priority in implementing your Bushfire Survival plan in these conditions.
  • For maximum probability of survival, leaving early on a day of Extreme fire danger is the best option.
  • If your Bushfire Survival Plan includes the decision to stay and defend, only do so if your home is prepared to the highest level and constructed to withstand bushfire, and you are physically able to do so.
  • Stay well informed of the current fire situation throughout a day of catastrophic fire danger by remaining tuned to local media on a battery powered radio.

 

Severe

50–74

  • Fires can be difficult to control and will burn unpredictably. Embers will be blown around and it will be uncomfortable and dangerous to be out in the open.
  • There is a potential for property in the path of the fire, or impacted by ember attack to be lost, and people may suffer serious if not life threatening injury.
  • Only very well prepared homes and substantial, solid construction buildings will be likely to offer any degree of safety.
  • Expect localised power, telephone and water supply failure.
  • Do not expect a fire truck or firefighters to attend.

 

  • Ensure that your survival is the first priority in implementing your Bushfire Survival Plan in these conditions.
  • For maximum probability of survival, leaving early is the best option.
  • If your Bushfire Survival Plan includes the decision to stay and defend, only do so if your home is well prepared and constructed to withstand bushfire, and you are physically able to do so.
  • Stay well informed of the current fire situation throughout a day of Extreme fire danger by remaining tuned to local media on a battery powered radio.

Very High

25–49

  • Fires can be difficult to control. Embers may be blown around.
  • Loss of property and injury is less likely, but significant damage could occur.
  • Well prepared homes and substantial buildings can offer safe shelter.
  • Some local infrastructure may be temporarily unavailable.
  • Implement your Bushfire Survival Plan. Leaving early is the best option.
  • If your Bushfire Survival Plan includes the decision to stay and defend, only do so if your home is well prepared and constructed to withstand bushfire, and you are physically able to do so.
  • Stay well informed of the current fire situation Very High fire danger by remaining tuned to local media on a battery powered radio.

High

12–24

  • Fire can be controlled.
  • Loss of property is unlikely but damage may occur.
  • Well prepared homes and substantial buildings can offer safe shelter.
  • Stay well informed of the current fire situation throughout a day of High fire danger by remaining tuned to local media.
  • Know how to get further information if required.

Low-Moderate

0–11

  • Fire can be easily controlled.
  • Little risk to life and property.
  • Stay well informed of the current fire situation throughout a day of Low-Moderate fire danger by remaining tuned to local media.
  • Know how to get further information if required.