While three persons, including a woman, died in Ballia district, one death each was reported from Maharajganj and Barabanki districts, officials said.
Normal life was thrown out of gear as dense fog enveloped most parts of the state, with Muzaffarnagar remaining the coldest place with a minimum temperature of 3.2 degrees.
Temperature remained below normal in various parts of the state including Varanasi, Allahabad, Kanpur, Agra and Meerut divisions.
Meanwhile, the Lucknow district administration has ordered closure of all schools upto class Eighth till January 5.
In Barabanki also, all schools will remain closed till January 10 as per the order of the district administration.
Urban Development Minister Azam Khan has directed the authorities to ensure arrangement of bonfires at public places and shelters for those living on footpaths during night hours.
The Met office forecasts that cold wave conditions will continue to prevail in the state, which is also likely to witness a foggy weather during the next two days.
