1970 Bhola cyclone
The 1970 Bhola cyclone was a devastating tropical cyclone
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...

 that struck East Pakistan
East Pakistan
East Pakistan was a provincial state of Pakistan established in 14 August 1947. The provincial state existed until its declaration of independence on 26 March 1971 as the independent nation of Bangladesh. Pakistan recognized the new nation on 16 December 1971. East Pakistan was created from Bengal...

 (now Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...

) and India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

's West Bengal
West Bengal
West Bengal is a state in the eastern region of India and is the nation's fourth-most populous. It is also the seventh-most populous sub-national entity in the world, with over 91 million inhabitants. A major agricultural producer, West Bengal is the sixth-largest contributor to India's GDP...

 on November 12, 1970. It was the deadliest tropical cyclone ever recorded, and one of the deadliest natural disaster
Natural disaster
A natural disaster is the effect of a natural hazard . It leads to financial, environmental or human losses...

s in modern times. Up to 500,000 people lost their lives in the storm, primarily as a result of the storm surge
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...

 that flooded much of the low-lying islands of the Ganges Delta
Ganges Delta
The Ganges Delta is a river delta in the South Asia region of Bengal, consisting of Bangladesh and the state of West Bengal, India. It is the world's largest delta, and empties into the Bay of Bengal...

. This cyclone was the sixth cyclonic storm of the 1970 North Indian Ocean cyclone season
1970 North Indian Ocean cyclone season
The 1970 North Indian Ocean cyclone season had no bounds, but tropical cyclones in the North Indian Ocean tend to form between April and December, with peaks in May and November. The 1970 season saw a total of seven cyclonic storms, of which three developed into severe cyclonic storms...

, and also the season's strongest, reaching a strength equivalent to a strong Category 3 hurricane
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...


The cyclone formed over the central Bay of Bengal
Bay of Bengal
The Bay of Bengal , the largest bay in the world, forms the northeastern part of the Indian Ocean. It resembles a triangle in shape, and is bordered mostly by the Eastern Coast of India, southern coast of Bangladesh and Sri Lanka to the west and Burma and the Andaman and Nicobar Islands to the...

 on November 8 and travelled north, intensifying as it did so.