Ideal conditions for storing onions is

Ideal conditions for storing onions are 0°C and 70% RH.
Storage of onion bulbs in a cold store with optimum relative humidity extends the shelf life of onion bulbs and reduces post-harvest storage losses. The optimal storage temperature in cold storage is 0°C with 65 - 70% relative humidity. Under these conditions, the storage losses after six months are only about 5% which is mainly due to moisture loss. Regular monitoring of both temperature and relative humidity in the store is necessary to avoid significant fluctuations in environmental conditions.