Between 2014–15 and 2018–19, climate conditions led to an increase in the average and maximum Fire Danger Index (FDI). There was also an increase in the number of days with a very high Fire Danger Rating (FDR) from 11 days in 2014– 15 to 44 in 2018–2019. The 2018–19 fire season had the highest fire danger, with the greatest number of very high and high FDR days, and the highest maximum FDI. Climate change is expected to increase both average and severe FDI in the future.
Indicator assessment legend
Environmental condition is healthy across the ACT, OR pressure likely to have negligible impact on environmental condition/human health.
Environmental condition is neither positive or negative and may be variable across the ACT, OR pressure likely to have limited impact on environmental condition/human health.
Environmental condition is under significant stress, OR pressure likely to have significant impact on environmental condition/ human health.
Data is insufficient to make an assessment of status and trends.
Adequate high-quality evidence and high level of consensus
Limited evidence or limited consensus
Evidence and consensus too low to make an assessment
Assessments of status, trends and data quality are not appropriate for the indicator
The Fire Danger Index (FDI) assesses the potential severity of bushfire occurrence given the predicted conditions. The FDI reflects the difficulty of suppression should a fire occur, and also the risk to community, property and landscape. FDI is determined by the Bureau of Meteorology based on forecast air temperature, relative humidity and wind speed, along with drought conditions and soil moisture levels. It should be noted that FDI does not reflect the observed conditions on the day, which may differ from those forecasted. The FDI is used to determine the Fire Danger Rating which provides a simplified indication of potential fire consequences (Table F1).
Table F1: Fire Danger Index scores and Fire Danger Ratings used for fire risk in the ACT.
|Fire Danger Index range||Fire Danger Rating|
|25–49||3 Very High|
The FDI expresses bushfire potential using a number scale. An FDI of 1 means a very low risk of fire occurring and that it will be easy to control; an FDI of 100 means that fires will have the potential to be so severe that control is virtually impossible. Elevated fire danger conditions (severe, extreme or catastrophic) occur when the FDI is greater than 50. Days of elevated fire danger conditions are not common in the ACT, averaging less than three days a year, usually in January.Emergency Services Agency, 2019, Strategic Bushfire Management Plan 2019–2024, ACT Government, Canberra. However, climate change is expected to increase both average and severe FDI in the future.
Condition and trends
Over the 2014–15 to 2018–19 period, the average and maximum FDIs have increased (Figure F6). Whilst this timeframe is too short to suggest an ongoing trend, it does show a growing fire danger in the ACT over the period. The 2018–19 fire season had the highest fire danger over the reporting period, with the greatest number of very high and high days, and the highest maximum FDI.
The data also shows that:
- the number of days with a very high FDR showed the greatest increase over the period, from 11 days in 2014–15 to 44 in 2018–19.
- the highest FDR over the period was severe, occurring on 11 days including 4 days in 2016–17 and 3 days in 2018–19; extreme and catastrophic ratings were not forecast.
- the highest forecast FDI in the period was 73, occurring in February 2019, followed by 72 in January 2019, and 63 occurring in both February 2018 and January 2017, and
- days of high, very high and severe FDR occur most often in January (104 days), followed by December (93 days).