Australian Severe Weather Outlook 2019-20

The science of cyclones

Tropical cyclones are low pressure systems that form over warm tropical waters and have gale force winds (sustained winds of 63 km per hour or greater and gusts in excess of 90 km per hour) near the centre. Read more about tropical cyclones

The Bureau of Meteorology maintains a resource of current tropical cyclones in Australia, as well as information on the science and formation of cyclones, safety information and an outline of warning services. 

Additional capability and research information is available from Geoscience Australia

Storm surge

A storm surge is a rise above the normal water level along a shore resulting from strong onshore winds and/or reduced atmospheric pressure. Storm surges accompany a tropical cyclone as it comes ashore. They may also be formed by intense low-pressure systems in non-tropical areas. Around the world, drowning by storm surge accounts for a high proportion of the deaths in tropical cyclones.

Know more about storm surges, including preparedness and safety.

Understanding tropical cyclone categories

Tropical cyclone intensity is defined by the maximum mean wind speed over open flat land or water. This is sometimes referred to as the maximum sustained wind and will be experienced around the eye-wall of the cyclone.

Know more about intensity and impacts, including the Tropical Cyclone Category System and the Beaufort Scale.

Bureau of Meteorology

How and why do we give cyclones names?

Bureau of Meteorology

Being safe in an area where cyclones occur

Under Australia's emergency management arrangements, state and territory organisations are the primary agencies responsible for earthquake safety. Typically, these responsibilities rest with the State Emergency Services or combined emergency service agencies. The links below provide information from relevant agencies in states and territories that are regularly affected by cyclones.

Northern Territory

The Top End of the Northern Territory is naturally prone to tropical cyclone events with some two to three cyclones affecting the region between November and April each year. The cyclone season officially commences on 1 November and ceases on 30 April, but cyclonic events have been known to occur outside this period. Cyclones usually affect coastal areas up to 50km inland from the sea, so whether you live in the city or the rural area, learning to protect yourself, your family and your property from cyclones can assist in minimising the potential losses and trauma that you might suffer.


Cyclones and severe storms can produce hail, flooding rains, lightning, winds greater than 200 kilometres per hour and storm surge. Pay attention to weather forecasts during storm season (November–April) — keeping informed will help you protect your family and property. Prepare your home for cyclones and severe storms before they happen.

Western Australia

Experiencing a cyclone can be frightening and traumatic. A cyclone is a low pressure system that forms over warm tropical waters, characterised by wind gusts of up to 280 kilometres per hour around a calm centre. These strong winds can cause injury, loss of life, major structural damage to communities, disruption of utility and telecommunication services, and turn debris into dangerous missiles.

In Western Australia, cyclone season starts in November and continues through to April. During this time coastal regions are at risk of being impacted by cyclones. Cyclone activity produces strong onshore winds and flooding rains increasing the threat of storm surge a rapid rise in sea level that accompanies a cyclone as it moves ashore. People may be at risk of drowning or fatal injury during or after a cyclone by collapsing buildings and moving debris during severe winds.