This is a seasonal issue. During the rains shelf life of Onions decreases as they start to sprout. So the onion stock is sold off in may, just before the monsoo

This is a seasonal issue. During the rains shelf life of Onions decreases as they start to sprout. So the onion stock is sold off in may, just before the monsoon. After May, monsoon rains start and they are heavy rains with lot of humidity. This leads to less onion being available. By the time we hit July, onion prices hit the roof. Then again by end of August/mid September, prices start softening. By the time next crop is ready (i.e. end of september) prices dive back to May levels of INR 8 per kg in the wholesale market.