New Delhi: Delhi and neighbouring plains shivered under a "severe" cold on Monday and large swathes of them battled a dense to very dense fog as the Met department predicted the conditions to persist over the next few days.
A severe cold wave gripped the region with the maximum temperature plummeting 10 degrees below normal in Delhi.
Meteorologists attributed the sharp drop in day temperatures to frigid northwesterly winds barrelling through the plains and reduced sunshine due to foggy weather.
In Delhi, dense fog lowered visibility to 50 metres in some areas, affecting road and rail traffic.
Ten trains were reported running late by 1.45 to 3.30 hours, a Railway spokesperson said.
The mercury dropped to 3 degrees Celsius in the Ridge area, 4.9 degrees below normal, making it the coldest place in the national capital.
The Ridge and the Ayanagar weather stations recorded a minimum temperature of 4 degrees Celsius and 4.1 degrees Celsius, respectively.
The Safdarjung observatory, Delhi's primary weather station, logged a minimum temperature of 5 degrees Celsius -- three notches below normal.
The Palam observatory recorded a minimum temperature of 6.5 degrees Celsius and a maximum of 12.5 degrees Celsius, a departure of nine degrees Celsius from normal.
Jafarpur in southwest Delhi logged a minimum temperature of 4.2 degrees Celsius and a maximum of 11 degrees Celsius, 10 notches below normal.
Mungeshpur in northwest Delhi recorded a minimum temperature of 5.3 degrees Celsius and a maximum of 11.4 degrees Celsius against the season's normal maximum temperature of 21.4 degrees Celsius.
The automatic weather stations at Ayanagar, Lodhi Road, Ridge, Najafgarh, Pitampura, and Mayur Vihar recorded a maximum temperature of six to eight notches below normal.
Mahesh Palawat, vice president (meteorology and climate change), Skymet Weather, said a western disturbance led to a fresh spell of snowfall in the mountains on December 25-26 and cold northwesterly winds are now sweeping through the plains after its retreat.
"An increase in the humidity levels due to the WD resulted in dense to very dense fog which reduced the sunshine, pulling down the day temperature further," he said. Palawat said the wind chill factor -- a measure of the rate of heat loss from skin that is exposed to the air -- is also high.
The higher the wind speed during cold weather, the colder it feels on the skin if a person is outside.
Delhi clocked a top wind speed of 15 kilometres per hour on Monday.
Biting cold conditions and dense fog were reported in several parts of Punjab and Haryana, with Narnaul being the coldest in the region at 2.4 degrees Celsius.
In Haryana, Hisar recorded a piercing cold as the minimum temperature plunged to 2.5 degrees Celsius. Ambala recorded a low of 7.7 degrees Celsius, Karnal 6.8 degrees Celsius, Rohtak 6.6 degrees Celsius, Bhiwani 5.5 degrees Celsius, and Sirsa 5.2 degrees Celsius.
Chandigarh, the joint capital of Punjab and Haryana, recorded a minimum temperature of 7.4 degrees Celsius.
In Punjab, Amritsar recorded a low of 6.5 degrees Celsius, Ludhiana 6 degrees Celsius, Pathankot 8.8 degrees Celsius, Bathinda 3.6 degrees Celsius, Faridkot 6 degrees Celsius, and Gurdaspur 4.5 degrees Celsius.
Intense cold conditions and fog affected normal life in parts of Rajasthan on Monday.
At a minimum temperature of minus 1.5 degrees Celsius, Fatehpur was recorded as the coldest place in the desert state followed by Churu and Pilani (Jhunjhunu) where the mercury settled at 0 degree Celsius and 0.2 degree Celsius respectively on Sunday night, according to the Met department.
Karauli and Sikar recorded a minimum of 0.5 and 1 degree Celsius while the night temperature was 2 degrees Celsius in Alwar, 2.4 in Bikaner, 2.7 in Bhilwara, 3 in Nagaur, 4.4 in Sriganganagar, Sangaria (Hanumangarh) and Vanasthali (Tonk), 4.5 in Dholpur and Anta (Baran), 4.7 in Chittorgarh, 5 in Dabok (Udaipur), 5.2 in Phalodi (Jodhpur) and 5.5 degree Celsius in Bundi.
The maximum temperature in most of the places in the state was recorded between 16 and 25 degree Celsius.
Very dense fog also occurred in isolated areas.
Bathinda in Punjab and Bikaner in Rajasthan reported zero visibility, while it dropped to 50 metres and below at Ambala, Hisar, Amritsar, Patiala, Ganganagar, Churu and Bareilly.
Foggy conditions will persist in these areas over the next few days, the India Meteorological Department (IMD) said.
According to the IMD, 'very dense' fog is when visibility is between 0 and 50 metres, 51 and 200 metres is 'dense', 201 and 500 'moderate', and 501 and 1,000 'shallow.'
In the plains, the IMD declares a cold wave if the minimum temperature dips to 4 degrees Celsius. A cold wave is also declared when the minimum temperature is 10 degrees Celsius or below and is 4.5 notches below normal.
A 'severe' cold wave is when the minimum temperature dips to two degrees Celsius or the departure from normal is more than 6.4 degrees Celsius.