The western current gets blocked on its way to enter into the peninsula by the western ghats which rise the currents to heights. This creates precipitation giving out rain to the western coast of the peninsula. Kerala, Karnataka, Goa and particularly Mumbai's continuous pouring are all because of this monsoon. Another part moves into the northern region providing rainfall over there.
The eastern part flows through Bay of Bengal picking up moisture and delivering rain to the Eastern and North Eastern ranges. One point to be noted is that monsoons are heavy currents. Unless there is a blockage on their way which ramps their flow to heights where the moisture can precipitate and give rain monsoons are not much use. Fortunately India has mountain ranges in steps like western, eastern ghats, Vindhyas and others which take their fair share of rains. Finally the whole current is blocked by the Big Daddy Mr.Himalayas draining all the currents and creating heavy rainfall on it's range.