The thick blanket of fog disrupted road, rail and air traffic in several areas, while sub-zero temperatures in the mountains kept people indoors.
Mercury dipped to six degrees from yesterday's 7.2 degrees in Kanpur.
In Delhi, a dense fog throughout the night reduced visibility to around 100 metres making operation of flights and running of trains virtually impossible. Several flights and trains were cancellation or rescheduled.
Railway sources said majority of trains in Haryana, Punjab, Delhi, Chandigarh and parts of Uttar Pradesh were running behind schedule by several hours and traffic on various national and state highways moved at a slow speed.
A Sonepat report said a number of daily commuters travelling between Panipat, Sonepat and Delhi were stranded at different railway stations in the region.
In Rajasthan, Mount Abu recorded temperature below freezing point causing bursting of some pipelines. The famous Nakki lake was frozen.
Churu recorded a minimum of two degrees Celsius followed by Bikaner and Sriganganagar with 3 degrees, Dholpur 4 degrees, Pilani 6, Barmer 8, Jaisalmer and Jaipur 9 degrees each and Ajmer 10 degrees Celsius.