Visibility was low in the cities but the situation was far worse in the outskirts and on the highways, the Met said. Many trains were running late and air traffic has also been badly hit.
The state police has issued an advisory to people not to speed on highways and drive slowly and carefully.
Traffic personnel have been alerted to ensure that drivers put on blinkers and fog lights. Normal life here has been disrupted due to the cold wave and fog.
The Met has predicted that the foggy conditions will prevail for the next one week or more.
Regional Director of the Met Office, J.P. Gupta, however, said that there could be some sunny afternoons in between. The maximum temperature was likely to hover between 16-17 degrees Celsius.
Lucknow recorded a minimum of 7 degrees Celsius, Gorakhpur (6.4), Allahabad (6), Kanpur was coldest at 5.3 degrees Celsius, Jhansi was 7.8 and Varanasi 7 degrees Celsius.