The deaths were reported from Bahraich (2), and one each from Shravasti and Balrampur.
Rae Bareli, around 80 km from here, was the coldest in the state with minimum temperature recorded at 3 degrees Celsius.
The deaths were reported from Bahraich, Shravasti and Balrampur.
Due to intense cold conditions, Lucknow District Magistrate Anurag Yadav has postponed to Jan 19 the reopening of schools after winter vacation.
The Met Office here said that the maximum temperature Tuesday was 12.5 degrees Celsius (9 degrees below previous day's maximum) and the minimum was 8.3 degrees Celsius, making for one of the coldest day.
Met Office director J.P. Gupta said there would be no respite from cold for the next few days as rainfall in the state has added to the winter chill.
Many trains, including Swarna Shatabdi and Lucknow Mail between Delhi and Lucknow, were running several hours behind the schedule due to dense fog, a railway officials said.
Officials said Jet Airways has cancelled its 9W 303/304 Lucknow-New Delhi flight and Indigo Airlines its 6E 444/445 Lucknow-Mumbai flight till Jan 31 owing to inclement weather. Indigo Airlines' 6E 446/449 flight between Lucknow and New Delhi and Spice Jet's S4-419 Lucknow-Delhi-Mumbai flight were also cancelled till Feb 10.