The 1991 North Indian Ocean Cyclone season was an extremely deadly and destructive season causing the deaths of more than 138,000 people and over $1.5 billion in damages. It was the period in which tropical cyclones formed to the north of the equator in the Indian Ocean. During the season tropical cyclones were monitored by the India Meteorological Department (IMD) and the Joint Typhoon Warning Center. The IMD assigned all depressions that it monitored with BOB followed by a number in numerical order. The JTWC also assigned a number and either the letter A or B depending on where the depression was when the first advisory was issued.

The 1991 Bangladesh cyclone was among the deadliest tropical cyclones on record. Forming out of a large area of convection over the Bay of Bengal on April 24, the tropical cyclone initially developed gradually while meandering over the southern Bay of Bengal. On April 28, the storm began to accelerate northeastwards under the influence of the southwesterlies, and rapidly intensified to super cyclonic storm strength near the coast of Bangladesh on April 29. After making landfall in the Chittagong district of southeastern Bangladesh with winds of around 250 km/h (155 mph), the cyclone rapidly weakened as it moved through northeastern India, degenerating into a remnant low over the Yunnan province in western China.