Satellite imagery showed some reduction in fog over Bihar and eastern Uttar Pradesh

However, 'dense' to 'very dense' fog prevailed in parts of Punjab, Haryana, west Rajasthan, Bihar, Delhi, west Uttar Pradesh, Jharkhand, Odisha and Assam

A spokesperson for the Indian Railways said 18 trains arriving in Delhi were delayed by up to six hours due to foggy weather

At 5:30 am, visibility levels stood at 25 metres in Patiala, Amritsar, Ambala, Hisar, Bikaner and Purnia and 50 metres in Churu, Ganganagar, Jhansi, Ranchi, Paradip and Lakhimpur

At the Palam Observatory near the Indira Gandhi International (IGI) Airport in Delhi, visibility was limited to only 50 metres. However, it improved to 350 metres by 8:30 am

Early-morning foggy weather in north and northeast India has heavily impacted road, rail and air traffic over the last fortnight

The IMD said 'dense' to 'very dense' fog and 'cold day' to 'severe cold day' conditions are likely to prevail over north India for the next five days

"Cold wave to severe cold wave conditions are likely to continue over northwest India for five days," it said

In the plains, the MeT office declares a 'cold wave' if the minimum temperature dips to 4 degrees Celsius or when the minimum temperature is 10 degrees or below and is four-and-a-half notches below the normal