What are cyclones?

Cyclones (called tropical cyclones in Australia, hurricanes in North America, and typhoons in East Asia) are intense low-pressure storm systems that form over warm tropical seas. In Australia they typically affect the north of the country, including the Northern Territory, the Kimberley and Pilbara regions of Western Australia, and the Queensland coast, between November and April.

Cyclones are rated on a five-category scale by the Bureau of Meteorology, with Category 1 the weakest (gusts up to 125 km/h) and Category 5 the most destructive (gusts above 280 km/h). Severe cyclones generally describe Categories 3, 4, and 5. The Australian region typically sees about 11 named cyclones per season, of which around 4 cross the coast.

The most destructive cyclone in Australian history was Tropical Cyclone Tracy, which struck Darwin on Christmas Eve 1974. Tracy killed 71 people and destroyed about 70 per cent of Darwin's buildings, prompting the city's complete evacuation and rebuilding under stricter cyclone-resistant codes. Other major cyclones include Cyclone Mahina (1899, the deadliest at about 300 deaths), Cyclone Yasi (2011, the largest by area), Cyclone Larry (2006, Innisfail), Cyclone Debbie (2017, Whitsundays), and Cyclone Jasper (2023, far north Queensland).

Cyclone Alfred made landfall near Brisbane and the Gold Coast in March 2025, the first cyclone to cross south-east Queensland and northern New South Wales since Cyclone Wanda in 1974. Climate change is shifting cyclone risk further south as ocean temperatures rise. Cyclone-prone areas are subject to specialised building codes and storm-surge mapping, and households are encouraged to prepare emergency kits and shelter plans before each cyclone season starts in November.