The December 6th Koolewong Fires
Tens of thousands of fires burn in Australia every year. Although most of these are occurring in the northern part of the country and in remote, unpopulated regions, some do occur in populated areas. The December 6th Koolewong fires are a telling example of those.
The 2025/26 fire season is well and truly underway for the southeastern part of the country. We have previously reported that more than 72% of historical damaging bushfires in NSW occurred during the summer months [1]. Together with spring, the two seasons make up more than 95% of historically damaging fires. Summer bushfires account for 75% of aggregate house losses for the state. At the time of writing this article, the Koolewong fires burned around 129 ha, destroying 16 homes and damaging 23 others [2].
Timeline
Here is a brief timeline of the Koolewong fires:
- Friday 5th: the NSW Rural Fire Services issued a Total Fire Ban for a large part of the state,
including the Greater Sydney Region (see Figure 2Figure 2). - Saturday 6th afternoon (around 1pm): the fire started and four houses were destroyed.
- Saturday late afternoon: the wind direction changed from a southeasterly to a northerly wind.
- Saturday early evening: the fire jumped south over water to Woy Woy Bay. The distance between the two fire footprints is over 600m (see Figure 5Figure 5).
- Saturday evening (around 7:30pm): some light rain provided relief and the increased humidity helped absorb heat from the fires. 2.8mm of rain was recorded at Gosford meteorological station from Saturday 6th at 9am to Sunday 7th at 9am.
- Sunday 7th morning: the State and Federal Governments activated a Natural Disaster Declaration. This ensured impacted residents have access to immediate and long term supports.
- Monday 8th: the Koolewong fires were officially downgraded to Advice level.
Cause
The cause of the Koolewong fires is currently unknown.
On December 6th, the Brisbane Water Police District established Strike Force Inola. The Strike Force is supported by the State Crime Command’s Arson Squad, Forensic Evidence Technical Support Command, and specialists from the NSW RFS and Fire and Rescue NSW [3].
As of December 10th, the investigators think the fire may have originated in bushland on Nimbin Avenue (see Figure 3). Given the proximity to the urban area, arson was one of the causes investigated. However, forensic examination at the point of origin has not found any evidence of ignitable liquids or deliberate ignition [3].
Impact
The Koolewong fires are composed of two main fire footprints. The smaller footprint in Woy Woy Bay resulted from spotting from the main fire that impacted Koolewong: some embers were transported over 600m in the afternoon of Saturday 6th.
To date, the Koolewong fires have destroyed 16 homes and damaged 23 others. It is expected that all these homes are in the Koolewong footprint and no loss occurred on the Woy Woy Bay fire. This is supported by Risk Frontiers’ internal analysis of the estimated fire perimeters.
Risk Frontiers has extracted the building centroids within the fire perimeters and computed the probability of destruction for each of the buildings using our FireAUS 4.0 vulnerability module (Figure 4 and Figure 5). That probability is calculated based on the local conditions at each exposure point including the distance to bushland, the amount of bushland surrounding the exposure (a proxy for how deep within the bushland the exposure is), the number of buildings and total built footprint surrounding the exposure, the effective slope and roughness of the location. These predictors are then run through Risk Frontiers’ Machine Learning damage model which estimates the probability of total loss. The model was trained on past detailed loss data that Risk Frontiers accumulated over the past three decades through ground surveys and high resolution pre- and post-disaster images.
¹ This exercise is part of a broader rapid loss estimation capability that Risk Frontiers has been developing and deploying over the past few years [1], [2].
Recovery
In the aftermath of the Koolewong fires, Local, State and Federal Governments have implemented disaster relief plans [4], [5]. The Minns and Albanese Governments on December 7th jointly activated a Natural Disaster Declaration. This declaration enables support to be made available under the joint Commonwealth-State Disaster Recovery Funding Arrangements (DRFA). It provides assistance to communities in the following ways:
- Assistance for eligible residents to help meet immediate needs such as emergency accommodation and essential items.
- Grants for low-income, uninsured residents to replace lost essential household items to maintain a basic standard of living.
- Grants for low-income, uninsured residents to undertake essential structural repairs to restore their homes to a basic, safe and habitable condition.
- Loans for non-profit organisations up to $25,000.
- Financial support towards counter-disaster activity undertaken by emergency service organisations to keep communities safe.
The State and Federal governments are also providing the Central Coast Council with support to remove debris and for the reconstruction of essential public infrastructure.
On December 10th the Central Coast Council resolved to action a range of supports to assist affected residents. These included:
- the establishment of a bushfire recovery program to a maximum value of $1 million AUD.
- The establishment of a pre-DA building advisory and development assessment service
- support for owners to mitigate expenses for waste disposal.
- delivery of skip bins to the affected bushfire site.
Since then, the Central Coast Council’s resolution recovery efforts have already begun. Skip bins have been delivered to the Koolewong exclusion area, and replacement bins have begun being delivered where bins were destroyed.
REFERENCES
[1] Briefing Note 492: An Eventful Start to the Fire Season on the East Coast
[2] Briefing Note 514: Tropical-Cyclone-Alfred-What-did-we-learn
[3] NSW Police: Update on Koolewong fires – Strike Force Inola
[5] https://www.centralcoast.nsw.gov.au/council/council-news/highlights-councils-december-2025-meeting
