Tropical Cyclone Hazard Assessment (TCHA)

Geoscience Australia has released a new Tropical Cyclone Hazard Assessment - the TCHA18. The TCHA18 is freely accessible and is available to download. The TCHA18 consists of four products:

The national Tropical Cyclone Hazard Assessment (TCHA) defines the severe wind hazard posed to Australia based on the frequency and intensity of tropical cyclones making landfall around the Australian coastline.

The TCHA provides vital information to emergency managers, town planners and infrastructure owners to plan and reduce the threat of tropical cyclone hazard on the Australian coast, and for the insurance industry to understand the tropical cyclone risk as an input to pricing insurance premiums.

The TCHA is a key data source to calculate local cyclone impact models for the development of evidence-based disaster management plans, evacuation plans or inform infrastructure planning or mitigation strategies.  High risk areas can be identified and prioritised for further analysis, or to extract scenarios to explore risk mitigation and community safety at a local and regional level.

Geoscience Australia provides essential evidence based information to government and emergency managers around Australia to improve our communities' ability to prepare for, mitigate against and respond to natural disasters. Contact us at if you need further information.

The TCHA has had a major update to include scientific advances in understanding tropical cyclone hazard including:

  • An upgrade to the methods that control the size of simulated tropical cyclones. The model relates size of the tropical cyclone to its intensity and latitude, providing a more realistic evolution of the size of the cyclones over their lifetime.
  • The model for determining how quickly tropical cyclones dissipate after landfall is now based on observations from Australia. Previously we used a simplified model based on United States landfalling hurricanes.
  • The model now stores the wind field from each individual synthetic tropical cyclone enabling users to extract and examine individual events.
  • An event database that records details of each synthetic event, the wind speeds arising from the event at locations around Australia and the likelihood of extreme wind speeds at those locations. This allows users to disaggregate the hazard information and explore scenarios impacting communities.

The new methodology was developed in consultation with industry, international research groups and government experts. We envisage that the TCHA18 will be considered in future revisions to the Australian wind loading standard, to ensure buildings and infrastructure are built to withstand tropical cyclone events.

Currently the assessment is for tropical cyclone winds only, and does not include other severe wind hazards such as tornadoes, severe storms or cyclones that transition into storm events. This is standard practice for tropical cyclone hazard assessments and recognised internationally as an agreed methodology. However, the scientific community understands this is a key constraint and is doing more research to address challenge.

Geoscience Australia will continue to update the TCHA, with the next revision schedule for 2021, as we recognise the importance of incorporating best practice and evidence based science, and there is still a lot to learn when it comes to tropical cyclone hazard in Australia. Science and technology is constantly evolving and improving, and we need to ensure the TCHA reflects these advancements so we can ensure Australian communities are as safe as possible from tropical cyclone events.

We welcome your feedback on the current TCHA18. Send you feedback to