Where it occurs
Tropical cyclones occur in the north of Australia closest to the equator. Western Australia between Broome and Exmouth and Northeast Queensland between Port Douglas and Maryborough. The tropic of capricorn runs through Western Australia and Northeast Queensland which means they are hot and tropic regions. This is why cyclones develop north of Australia as they are tropical areas and the oceans are the right temperature for cyclone to be formed.
This image was taken from http://www.bom.gov.au/cyclone/about/warnings/index.shtml. This image is showing the regions in Australia that get Tropical Cyclones.