Tropical cyclones in 1991

During 1991, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, a total of 100 systems formed with 75 of these developing further and were named by the responsible warning centre. The strongest tropical cyclone of the year was Typhoon Yuri, which was estimated to have a minimum barometric pressure of 895 hPa (26.43 inHg). The deadliest tropical cyclone was Cyclone BOB 01, which caused 138,866 fatalities in Bangladesh, Northeastern India, Myanmar, Yunnan, while the costliest was Typhoon Mireille, which caused an estimated $10 billion USD in damage after striking Japan. Four Category 5 tropical cyclones formed in 1991.

Tropical cyclone activity in each basin is under the authority of an RSMC. The National Hurricane Center (NHC) is responsible for tropical cyclones in the North Atlantic and East Pacific. The Central Pacific Hurricane Center (CPHC) is responsible for tropical cyclones in the Central Pacific. Both the NHC and CPHC are subdivisions of the National Weather Service. Activity in the West Pacific is monitored by the Japan Meteorological Agency (JMA). Systems in the North Indian Ocean are monitored by the India Meteorological Department (IMD). The Météo-France located in Réunion (MFR) monitors tropical activity in the South-West Indian Ocean. The Australian region is monitored by five TCWCs that are under the coordination of the Australian Bureau of Meteorology (BOM). Similarly, the South Pacific is monitored by both the Fiji Meteorological Service (FMS) and the Meteorological Service of New Zealand Limited. Other, unofficial agencies that provide additional guidance in tropical cyclone monitoring include the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) and the Joint Typhoon Warning Center (JTWC).