Due to the peculiar shape of the Indian peninsula, the southwest monsoon winds enter India by bifurcating into two branches -Arabian Sea branch and Bay of Bengal branch.
Arabian Sea Branch: The Arabian sea branch which reaches Kerala coast by the beginning of June gives heavy rainfall in the western parts of Kerala, Karnataka, Goa, and Maharashtra.
Bay of Bengal branch: The Bay of Bengal branch which absorbs moisture from Bay of Bengal advances through Sundarban delta and enters West Bengal and bifurcates into two. One branch enters the Brahmaputra plains and gives heavy rainfall in the northeastern states. Khasi, Garo hills obstruct the winds to cause rainfall.
The other branch enters the Ganga plains and gives rainfall in the states of West Bengal, Bihar, and Utter Pradesh. This branch joins with the Arabian Sea branch in the Punjab plain, moves northward and gives heavy rainfall in the foothills of the Himalayas.
