Twelve people - 9 in Uttar Pradesh and 3 in Punjab - died due to intense cold wave coupled with dense fog sweeping aross north India on Thursday.
According to UP officials, three persons were killed in Mainpuri and one each in Barabanki and Badaun districts in separate road accidents due to low visibility caused by fog.
Two each in Barabanki and Muzaffarnagar died due to cold wave.
Hilly regions of J-K and Himachal Pradesh reeled under temperatures below the freezing point, while dense fog in the plains caused low visibility affecting flight operations and delaying around 100 trains.
In the national capital, people woke up to a chilly Christmas morning with dense fog continuing to disrupt road, rail and air traffic. The minimum temperature in Delhi settled two notches below the season's average at 6 degrees Celsius.
The maximum was 15.9 degrees, according to the MeT office. More than 90 trains including Rajdhani Expresses coming from Ranchi, Kolkata, Bubhaneshwar and Guwahati were running late, railway officials said.
Shahjahanpur recorded the lowest minimum temperature in UP at 2.5 degrees Celsius, MeT officials said.
In Punjab, Amritsar was shivering at 3.2 degrees Celsius with dense fog disrupting normal life across the state and its neighbouring Haryana.
Three persons died in a jeep-truck collision in Punjab's Gurdaspur district. Police said low visibility caused by fog led to the accident.
Narnaul in Haryana was the coldest place in the state recording a minimum temperature of 3.3 degrees, three notches below normal. Karnal and Ambala also experienced the chill registering below normal lows of 5.8 degrees and 6.6 degrees Celsius, respectively.
Meanwhile, the Kashmir Valley reeled under sub-zero temperature as mercury settled at minus 3.9 degrees Celsius and in the cold desert of Ladakh it remained under the minus 10 degrees mark freezing most water bodies and fringes of the famous Dal Lake.
Kashmir is currently going through 'Chillai-Kalan', the period when the chances of snowfall are maximum and most frequent. Weather remains cold during this period as the day temperature also dip drastically.
Kargil town in Ladakh was the coldest recorded place in the state with a low of minus 12.6 degrees Celsius, a drop of over 2.6 degrees from the previous night. Night temperature also fell by two notches in the nearby town of Leh to settle at minus 12.0 degrees.
Minimum temperature in Srinagar dropped to minus 3.9 degrees. Pahalgam hill resort continued to be the coldest recorded place in Kashmir with a night temperature of minus 6.5 degrees Celsius. Gulmarg, the famous ski resort in north Kashmir, experienced a low of minus 6.4 degrees.
Intense cold continued in Rajasthan too, with thick blanket of fog adding to the people's woes.
Foggy conditions prevailed in areas like Pilani, Jaipur, Bikaner, Churu, Gangangar among others, MeT department said. Minimum temperature dipped to minus 0.5 degree Celsius in Bikaner district. Churu on the plains recored a minimum temperature of 4 degrees Celsius, while the low at Mount Abu, the hill resort in the state, settled at 4.6 degrees.
Meanwhile, high altitude tribal areas of Himachal Pradesh and mountain passes experienced another spell of moderate snowfall while icy winds swept the region.
Intense cold wave conditions continued in the state as mercury stayed below freezing point in tribal areas and higher hills while it rose marginally to stay a few notches above freezing point in mid and lower hills.