There is spatial and temporal variation of rainfall in India. Various factors contributed to this uneven distribution of rainfall in India.
(i) Relief Relief factors (e.g. high mountains and hills) act as a barrier to rain bearing winds. When such winds collide with the high mountains, they cause orographic rainfall on the windward side. The leeward side on the other hand remains drier, e.g. due to Western Ghat, the Western coastal plains get heavy rainfall.
(ii) Distance from the sea (Continentality) As the distance from the sea increases, the moisture content of the wind decreases. So, the interior of landmass are much drier than those in coastal region.
(iii) Direction of Wind The regions lying in the direction of flow of wind are rainier than those not lying on its direction, e.g. Tamil Nadu coast which lies parallel to Bay of Bangal branch does not get rainfall from South-West monsoon.