Temperatures across north India are expected to drop further during the upcoming weekend. (Photo: Reuters)

Several trains and flights were delayed on Thursday as an intense cold wave gripped most parts of north India including Delhi. The intense cold has also resulted in a deterioration of air quality in parts of the national capital.

At least 25 trains coming to Delhi have been delayed by two hours or more on account of dense fog in the morning while several flights were cancelled in the morning due to the ongoing cold wave across north India.

The minimum temperature recorded in Delhi today was at a five-year low of 6 degrees Celsius while the maximum temperature is expected to reach 15 degrees Celsius. The day is expected to remain partly cloudy throughout the day with wind speeds reaching up to 11 km/h.

Air quality levels in the national capital and surrounding regions also worsened today on account of dense fog. The air quality index in parts of Delhi touched very poor on Thursday and is expected to worsen as temperatures are expected to drop further during the upcoming weekend.

Delhi: People take refuge in night shelters as mercury level dips in the national capital; visuals from a night shelter near Safdarjung Airport flyover. pic.twitter.com/dU8wzEHQ2E ANI (@ANI) December 26, 2019

According to the weather department, Delhi could experience a minimum temperature of at least 5 degrees Celsius or lower on Friday.

The situation is expected to change from December 29 due to a possible change in wind direction from north-westerly to easterly. However, the minimum temperature is expected to drop to 4 degrees Celsius on December 28 and December 29.

From December 31, air pollution levels are also expected to reduce as there will be a significant increase in wind speed. Though unlikely, light rain has been predicted over Delhi-NCR late on December 31.

It is worth mentioning that the national capital has been witnessing the longest cold day spell in 12 years.

Cold day condition arises when the maximum temperature plummets by 4.5 degrees Celsius in winters while severe cold day condition arises when there is a decline of 6.5 degrees Celsius in maximum temperature.

Delhi: Air quality in 'Very Poor' category in Anand Vihar, Lodhi Road and India Gate circle areas, as per Central Pollution Control Board (CPCB). pic.twitter.com/oVJNJzwrqE ANI (@ANI) December 26, 2019

Since December 16, the national capital has registered nine cold days, equal to that recorded in 2003. The city recorded a maximum of 17 cold days in December 1997.