Cyclones in Australia. Cyclones are storms of powerful winds that commonly occur in Australia. As the cyclones blow out of the Pacific Ocean, many reach land, bringing strong winds and heavy rains. These storms frequently cause sea and river levels to rise, resulting in floods. The rising water levels are known as storm surges. Because of their weather effects, cyclones have been the source of some of Australia’s most devastating natural disasters. 
Causes of cyclones.
Cyclones occur when warm ocean air rises, which creates a low-pressure system. Air tends to move from areas of high atmospheric pressure to areas of low pressure, creating wind. As air flows into this system, it spins around and flows upwards into the center of the system. In the Southern Hemisphere, these winds move in a clockwise direction. 
As its rotating winds gain speed, the storm becomes bigger and more powerful. A cyclone’s intensity is measured using the Saffir-Simpson scale. The scale designates five levels of cyclones. Weaker storms are rated Category 1, while the most powerful are labeled Category 5. Individual storms can change category as they become more or less intense. Australia has experienced several Category 5 cyclones in its history, including Cyclone George in 2007 and Cyclone Yasi in 2011.
Predicting cyclones.
The cyclone season in Australia occurs between November and April. Each year’s cyclone season depends on the seasonal rainfall and temperatures of the ocean currents. Historically, the Northern Territory, Queensland, and Western Australia are the regions that have been most impacted by cyclones. 
Starting in 2022, the Australian Bureau of Meteorology has used the Australian Community Climate and Earth-Simulator (ACCESS) computer model to look for cyclones. The model also helps government and emergency management agencies predict the timing and strength of future cyclones.
Some major Australian cyclones.
This section describes some of the most destructive cyclones in Australian history.
Cyclone Mahina (1899).
The deadliest cyclone in Australia’s recorded history reached the northeastern coast of Queensland in March 1899. The cyclone was predicted by early meteorological (weather) instruments, but scientists were unable to contact ships in the region before they were hit by the storm. The area had a large fishing fleet due to its pearl-diving industry. As the storm reached Princess Charlotte Bay and Bathurst Bay on March 4, it sank many of these ships, killing more than 300 people.
Innisfail cyclone (1918).
On March 10, 1918, an unnamed cyclone swept through the town of Innisfail, Queensland. When the destruction settled, few buildings had survived the storm. Authorities believe that 37 people from Innisfail were killed by the cyclone. At least 60 people from surrounding communities died as well. The cyclone also caused a storm surge in Bingil Bay, leading to serious floods in and around the town of Mission Beach.
Great Gold Coast cyclone (1954).
This unnamed cyclone reached land on Feb. 20, 1954, when it passed over Coolangatta, Queensland. After battering the Queensland cities of Brisbane and Gold Coast, it moved south into New South Wales. Coastal communities—particularly Byron Bay and Lismore—experienced severe flooding in addition to other storm damage to buildings and infrastructure. More than 25 people were reported dead due to the cyclone and its accompanying floods.
Cyclone Tracy (1974).
The Northern Territory experienced its most devastating cyclone on Christmas Day, 1974. The storm hit the capital city of Darwin on the morning of December 25. Its winds reached over 125 miles (200 kilometers) per hour. At least 70 people were killed in the disaster. Most of Darwin’s buildings were seriously damaged or destroyed. The rescue and evacuation effort for Cyclone Tracy was one of the largest in Australian history. 
Cyclone Orson (1989).
Cyclone Orson formed off the Darwin coast in April 1989. It reached land on April 23, passing near the city of Karratha in Western Australia. Its internal pressure was the lowest ever recorded in an Australian cyclone. Low pressure is an indicator of a strong storm. Four people were killed by the storm while fishing off Australia’s northwestern coast near Ashmore Island.
Cyclone Ingrid (2005).
This small but powerful cyclone crossed the Queensland coast on March 10, 2005. As the storm became stronger, it moved into the Northern Territory, lashing islands off the coast of Arnhem Land. The cyclone gained and lost power numerous times as it traveled west, eventually hitting the Kimberley region of Western Australia and dying out. It is the only cyclone ever recorded to impact three Australian states or territories. While no deaths occurred in Australia, five people off the coast of Papua New Guinea died due to the storm.
Cyclone Yasi (2011).
This storm developed off the coast of Fiji in January 2011. It grew stronger as it moved westward. It was officially classified a cyclone when its powerful winds reached Australia. It passed over the coast near Mission Beach, Queensland, on February 3. The storm seriously damaged many smaller towns in the area, including Cardwell, Innisfail, and Tully. It caused flooding in coastal areas around Cairns. The storm caused one death. Cyclone Yasi also devastated many farms in Queensland. 
