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.

One of the most powerful tropical cyclones ever recorded in the basin, the tropical cyclone caused a 6.1 m (20 ft) storm surge, which inundated the coastline, causing at least 138,866 deaths and about US$1.7 billion (1991 USD) in damage. As a result of the catastrophic damage, the United States and other countries carried out Operation Sea Angel, one of the largest military relief efforts ever carried out.