How do the northeast and southwest monsoons affect the Bay of Bengal?

The climate and surface currents of the Bay of Bengal are fundamentally shaped by the seasonal reversal of the monsoons.12

The Northeast Monsoon (November–April)

During the winter season, a continental high-pressure system north of the bay generates northeasterly winds. This period is characterized by the Northeast Monsoon Drift, a surface current that flows toward the southwest and west. While much of the region experiences a drier season, the transition to this pattern in late autumn contributes to a rainy season for the extreme southeastern coast of the Deccan and eastern Sri Lanka, often influenced by tropical depressions and cyclones.123

The Southwest Monsoon (June–September)

In the northern summer, intense heating over the continent creates a low-pressure system, drawing moist air from the ocean and establishing the southwest monsoon. This flow reverses the surface currents, pushing the Southwest Monsoon Drift eastward and sending branches northward into the bay. This branch is a primary source of heavy rainfall for eastern India and Bangladesh, with its effects intensified by topography in areas like the Shillong Plateau.124