The northEast Monsoon extends from the second half of October through November. The average annual rainfall is 3266m.m.
Humidity is very high in the coastal region.
Rivers The Chaliyar Known in the lower reaches as the Beypore river, this is one of the major rivers of the state. The lower reaches form part of the West Coast Inland Navigation system. As an inter-state river, this has a total drainage area of 2923 sq.kms, of which 2532 sq.kms. Though small in size, the Kallai is one of the most important rivers in the entire state from the commercial point of view. Kallai, a main centre of timber trade, is situated on its banks.