The minimum temperature Monday was 4.4 degrees Celsius, three notches below the season's average.
Met Office director J.P. Gupta said the foggy conditions would continue this month.
Over 60 trains coming to Lucknow were delayed by several hours. Major trains coming to Lucknow, including Delhi-Lucknow Shatabdi Express, Kota-Patna Express, Dibrugarh-Chandigarh Express, Kaifiyat Express and many others, were running late, an official said.
Operation of at least 195 night buses of the Uttar Pradesh State Road Transport Corporation was cancelled due to poor visibility on highways, a transport official told IANS.
Two Delhi-bound flights of Spicejet and Indigo were cancelled Sunday and two morning flights Monday were delayed by an hour, airport official said.
While the maximum temperature Sunday was recorded at 20.6 degrees Celsius, the minimum was two notches below average at 6.2 degrees Celsius.