Northeast Monsoon season is the major period of rainfall activity over south peninsula, particularly in the eastern half comprising of the meteorological subdivisions of Coastal  Andhra Pradesh, and Tamilnadu. For Tamilnadu this is the main rainy season accounting for about 48% of the annual rainfall. Coastal districts of the State get nearly 60% of the annual rainfall and the interior districts get about 40%  of the annual rainfall.  Though the principal rainy season for  Interior Karnataka and Kerala  is the Southwest Monsoon season, rainfall continues till December in these sub-divisions, the period October-December (Northeast Monsoon ) contributing about 20 % of the annual total.