Lucknow, Dec 29 (IANS): Most parts of Uttar Pradesh were blanketed by a dense fog Monday morning. With the cold wave continuing unabated, return of fog compounded the inclement weather, and crippled rail and air transport.

More than four dozen trains were running late, with the Kota-Patna Express setting a new record of a 38-hour delay, railway officials said.

Officials said the dense fog on the outskirts had completely blinded the rail traffic, making it virtually impossible to maintain train schedules. For the safety of passengers, train drivers have been asked to exercise caution and as a consequence schedules have taken a hit, a Northern Railway official told IANS.

Trains like the Barauni Mail (13 hours), Nauchandi Express (11), Chandigarh Express (11), Amarnath Express (9), Kashi Vishwanath Express (6), Neelanchal (6), Punjab Mail (6), Shatabdi Express (3), Lucknow Mail (5) are running behind schedule, officials said.

Due to the dense fog, both in Delhi and in Lucknow, flights could only land at the Chaudhary Charan Singh airport in the state capital at around 1 p.m. Sunday.

The Air India Express flight from Dubai scheduled to reach the state capital 11.45 p.m. Saturday could only land at the airport only at 12.30 p.m. Sunday after a delay of over 12 hours

Five flights were cancelled Sunday, with no respite from fog and resultant poor visibility, the same scenario is likely to be repeated Monday, an official said.

The Regional Met Office said that the cold wave would continue and the foggy conditions would further intensify in the coming days. With day temperatures dropping to 11-12 degrees Celsius in most parts of the state, the cold wave is getting harsher with every passing day.

Vacations in all colleges in the city have been further extended and they would now open Jan 1, 2015, a district official said.