Wholesale traders said there is a substantial fall in supplies from two major producing states -- Maharashtra and Madhya Pradesh.
"During the lean period from June to September, demand of onions in northern India is met through supplies from Maharashtra and Madhya Pradesh, which have fallen sharply, leading to a hike in wholesale prices," Azadpur Mandi Onion Merchant Traders Association President Surendra Budhiraj said.
Wholesale prices have gone up to Rs 15-25 per kg from Rs 10-15 a few days ago, he said. The commodity is available at Rs 30-40 per kg in retail markets, depending on the location. Mother Dairy's Safal outlets are selling onion at Rs 29 a kg.
According to the latest daily report of the Department of Consumer Affairs on July 4, retail price of Rs 41 per kg in Port Blair was the highest in the country while the lowest was Rs 16 per kg in Jabalpur in Madhya Pradesh. The average price was around Rs 28 per kg.
According to the government's data, prices are on a higher side in eastern, southern and northern parts.
Cities where prices were on higher side include Aizwal at Rs 40, Rs 34 in Kolkata, Rs 33 in Thiruvananthapuram and Rs 32 each in Kozhikode and Shillong. The price is Rs 30 per kg in Chandigarh, Bhagalpur and Shimla, according to the data.
To check the price rise, the Centre has imposed minimum export price of USD 300 a tonne on onion to curb exports.
The government has brought onion and potato under the Essential Commodities Act. It has also decided to amend the law to make hoarding a non-bailable offence, besides setting up a price stabilisation fund to enable states to undertake market intervention.
Onion production is estimated to have risen to 192 lakh tonnes during 2013-14 crop year (July-June), from 168 lakh tonnes in 2012-13.
Meanwhile, exports fell to 13.58 lakh tonnes last fiscal, from 18.22 lakh tonnes in 2012-13.