List of Category 4 Australian region severe tropical cyclones
Category 4 the second-highest classification on the Australian tropical cyclone intensity scale which is used to classify tropical cyclones, that have 10-minute sustained winds of at least wind speeds of . 47 tropical cyclones have peaked Category 4 severe tropical cyclones in the Australian tropical cyclone basin, which is denoted as a part of the Indian and Pacific Oceans to the south of the equator and between 90°E - 160°E. The earliest tropical cyclone to be classified as a Category 4 severe tropical cyclone was Gyan which  was classified as a Category 4 during December 22, 1981, as it impacted New Caledonia. The latest was Pola as it passed between Fiji and Tonga. This list does include any tropical cyclones that peaked as a Category 5 severe tropical cyclone, while in the Australian region. Background. The Australian region tropical cyclone basin is located to the south of the Equator between 90°E and 160°E. The basin is officially monitored by the Australian Bureau of Meteorology as well as the Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), and the Papua New Guinea National Weather  Service. The United States Joint Typhoon Warning Center (JTWC) and other national meteorological services such as New Zealand's MetService, Météo-France and the Fiji Meteorological Service, also monitor parts of the basin in an unofficial capacity. Within the basin a Category 4 severe tropical cyclone is a tropical cyclone that has 10-minute mean maximum sustained wind speeds of on the Australian tropical cyclone intensity scale. A named storm could also be classified as a Category 4 tropical cyclone if it is estimated, to have 1-minute mean maximum sustained wind speeds of between on the Saffir-Simpson hurricane  wind scale. This scale is not officially used by any of the warning centres for the region, however, tropical cyclones are compared to it by various agencies including NASA. On both scales Category 5 tropical cyclones are expected to cause widespread devastation, if it significantly impacts land at or near its peak intensity. Over the years, the intensity estimates of tropical cyclones have been reanalysed for various reasons and were found to have been underestimated by the various warning centres. In particular, during a database repair project that took place between 2005 and 2007, the BoM discovered that Severe Tropical  Cyclone Pam of 1974, had been reanalysed at some point after 1979. This reanalysis showed that Pam had moved out of the South Pacific region and into the Australian region, as a category 5 severe tropical cyclone. However, a later reanalysis by the BoM during 2021 downgraded it to a category 4 severe tropical cyclone, as it was thought that the width of the southern eyewall was too narrow for a category 5 severe tropical cyclone.