Commuters make their way amid dense fog on a cold winter morning in Amritsar. In its latest impact-based advisory, the India Meteorological Department (IMD) said "severe" cold wave is expected over Punjab, Haryana, Delhi, Uttar Pradesh and northern Rajasthan from December 28 and there is increased likelihood of various illnesses like flu, running nose or nosebleed which usually set in or get aggravated due to prolonged exposure to cold.