New Delhi: Delhi on Sunday recorded the coldest night of the winter season for the second consecutive day with the mercury dropping to 3 degrees Celsius in Aya Nagar, the last village of Delhi on the Mehrauli-Gurgaon Road.

Cold and dense fog conditions will prevail in Delhi and the National Capital Region (NCR), the India Meteorological Department has issued a red alert.

Last night, Delhi grappled with cold wave conditions as the minimum temperature dropped to 3.9 degrees Celsius.

Various locations reported varying minimum temperatures, with Lodi Road recording 3.4 degrees, Safdarjung at 3.6 degrees, Ridge at 3.9 degrees, and Palam at 5.8 degrees, according to the IMD.

Meanwhile, as many as 18 Delhi-bound trains have been running late by 1-6 hours due to cold and fog in Delhi and many other parts of the country.

News agency ANI reported that several flight operations were delayed at the Delhi airport due to low visibility amid fog.

At 9 am, the Air Quality Index (AQI) in Delhi was recorded at 365, based on data from the Central Pollution Control Board (CPCB). The AQI scale categorises air quality as follows: 0-50 'good', 51-100 'satisfactory', 101-200 'moderate', 201-300 'poor', 301-400 'very poor', and 401-500 'severe'.

The Indian Meteorological Department (IMD) has issued a red alert for Punjab, Haryana, and Chandigarh due to prevailing weather conditions.

A yellow alert has been issued for Rajasthan, considering the cold and foggy conditions.

"Dense to very dense fog has been reported in isolated parts of Punjab and East Uttar Pradesh, while dense fog has been recorded in isolated pockets over Haryana, Delhi, Madhya Pradesh, Bihar, Assam, Gangetic West Bengal and Andhra Pradesh. Moderate fog was recorded in isolated pockets over Rajasthan and West Uttar Pradesh," the IMD said.