Elsewhere in the Kashmir Valley, the minimum temperature remained several degrees below the freezing point. A MeT department official in Srinagar said light rain or snow at isolated places in Jammu and Kashmir over the next 48 hours may add to the discomfort of the residents.
The minimum temperature in Srinagar was -3.9C.
Kashmir is under the grip of Chillai-Kalan - a 40-day harshest period of winter when snowfall is frequent and the temperature drops considerably. It ends on January 31, but the cold wave continues even after that in the Valley.
In Delhi, which experienced the coldest night of the season at 5C, dense fog curtailed visibility to less than 50 metres early morning today.
At least 92 trains were running late, 44 were rescheduled and 19 cancelled in New Delhi, a railways official said.
Flights moving in and out of the Indira Gandhi International Airport were badly hit. At least 198 flights were delayed and 11 cancelled, the airport officials said.
Himachal Pradesh shivered under biting cold wave as the mercury hovered around the freezing point at several places.
Bhuntar, Solan and Una experienced the coldest night of the season with mercury dropping to 0.4C, 0.5C and 1.4C respectively.
Water pipes froze and burst at many places, while ground frost occurred in other areas, affecting vehicular traffic.
High-altitude tribal areas and mountain passes groaned under arctic-like conditions, with the mercury staying up to 21 degrees below the freezing point. Keylong, Kalpa and Manali recorded a low of -9.4C, -3.4C and -2.2C respectively.
In Haryana, the state government today directed the deputy commissioners to ensure that no person sleeps in the open. The temperature in Narnaul in Haryana and Bathinda in Punjab settled at 1.5C and 2.8C.
A thick fog enveloped Chandigarh, where residents preferred to remain indoors as the temperature dropped to 5.2C.
Officials said fog delayed a number of trains passing through Punjab and Haryana. Flight operations were also hit.
In Uttar Pradesh, several parts recording a fall in the day temperatures. Muzaffarnagar recorded the lowest temperature at 3.4C, a MeT department official said in Lucknow. Dense to very dense fog occurred at isolated places in the northern state, he said.
Cold wave conditions prevailed at most places in Rajasthan as the northerly winds swept the state. Mount Abu, the only hill station in the desert state, was recorded the coldest last night where mercury touched the freezing point.
In plains, Alwar was recorded the coldest at 0.4C.