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The Australian fire danger ratings system explained

Anthony Sharwood, Thursday November 21, 2024 - 17:05 AEDT

With summer almost upon us, it's worth a quick reminder about the new national fire danger ratings system which came into effect on September 1, 2022.

Fire danger ratings describe the potential level of danger in the event that a bushfire starts.

Image: Each state and territory now uses this system. Source: AFAC.

Previously, the states and territories each had their own ratings system. Most states had five or even six levels of fire danger, and the number of ratings was sometimes confusing to the public.

For example, Western Australia had a "severe" rating as well as an "extreme" rating. Both categories sounded pretty serious, which meant people potentially would not change their behaviour between the two ratings levels.

But now, as mentioned, there are just four levels nationwide (with the recommended behaviour for those in fire risk areas in brackets):

Moderate: (Plan and prepare)

High: (Prepare to act)

Extreme: (Take action now to protect your life and property)

Catastrophic: (For your survival, leave bushfire risk areas)

How do fire authorities generate the ratings?

The ratings are updated daily and are generated by a combination of:

Observations about the current state of the bushfire fuel load

Weather forecasts

Fire behaviour models

Each of the four ratings fall within a numerical scale called the Fire Behaviour Index (FBI).

The FBI runs from 0 to 100 (and beyond). The higher the number, the higher the dangerous fire behaviour and therefore fire danger risk.

Image: Source: AFAC.

On days with moderate fire danger, people are advised to stay up to date and be ready to act if there is a fire. These are days with an FBI value between 12 and 23.

On days of high fire danger, there is a heightened risk and people should be alert for fires in their area and decide what they will do if a fire starts. If a fire does start, life and property may be at risk. The safest option is to avoid bushfire risk areas on these days. These are days with an FBI value between 24 and 49.

When there is extreme fire danger, conditions are dangerous, and people should reconsider travel through bushfire risk areas. Check bushfire plans and ensure that properties are fire-ready. If a fire starts, take immediate action. If any people or property are not prepared to the highest level under these conditions, head to a safer location well before the fire arrives. These are days with an FBI value between 50 and 99.

On days of catastrophic fire danger, life may depend on the decisions made, even before there is a fire. People should go to a safer location early in the morning or the night before if possible. Homes cannot withstand fires in these conditions and if a fire starts, people may not be able to leave, and help may not be available. These are days with an FBI value of 100 or higher.

Remember, while fire danger ratings provide vital information about the potential level of danger, they don’t guarantee that a fire will start, nor do they give any information about current fires.

For information about fires in your area, check the following websites in each of the states/territories:

ACT: ACT Emergency Services Agency

NSW: NSW Rural Fire Service

NT: Bushfires NT

Qld: Queensland Fire and Emergency Services

SA: SA Country Fire Service

Tas: Tasmania Fire Service

Vic: Country Fire Authority, Victoria

WA: Department of Fire and Emergency Services, WA

It's also worth mentioning that on days when there is minimal risk, such as on days with persistent widespread rain, you'll see the words 'No Rating' displayed on signs, apps and websites.

This is another change from the old system where the rating on such days was typically "low" or "moderate".

- Weatherzone

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The Australian fire danger ratings system explained

17:05 AEDT With summer almost upon us, it's worth a quick reminder about the new national fire danger ratings system which came into effect on September 1, 2022.