Severe Tropical Cyclone Glenda was among the strongest tropical cyclones to threaten Western Australia, though it weakened considerably before landfall and moved ashore in a lightly populated region. It began as a tropical low on 15 March in the Gulf of Carpentaria. The precursor disturbance drifted over Top End and later across the northeastern portion of Western Australia, and after emerging into the Indian Ocean it strengthened into a tropical storm. Aided by favourable environmental conditions, Glenda rapidly intensified to reach Category 5 status on the Australian cyclone scale, and with a peak intensity of 910 mbar it was among the strongest cyclones on record within the Australia region. On 30 March it moved ashore near Onslow as a Category 3 cyclone, and the next day it degenerated into a remnant tropical low over land.

Throughout 2006, 133 tropical cyclones formed in seven bodies of water known as tropical cyclone basins. Of these, 80 have been named, including two tropical cyclones in the South Atlantic Ocean, and a tropical cyclone in the Mediterranean Sea, by various weather agencies when they attained maximum sustained winds of 65 km/h (40 mph). The strongest storms of the year were Typhoon Yagi in the Western Pacific, and Cyclone Glenda of the Australian region. The deadliest and costliest storms of the year were a series of five typhoons that struck the Philippines and China; Chanchu, Bilis, Saomai, Xangsane, and Durian, with most of the damage being caused by Durian of November. So far, 27 Category 3 tropical cyclones formed, including five Category 5 tropical cyclones in the year. The accumulated cyclone energy (ACE) index for the 2006, as calculated by Colorado State University was 761 units.