Cold wave has tightened its grip in north India and there is no respite until the New Year. Temperature at various north Indian cities hit a new low including Delhi. IMD has issued red-coded warning - extreme weather events- for Punjab, Haryana, Delhi, Rajasthan, Uttar Pradesh and Bihar. Dense fog also worsened air, rail and road traffic. According to Railway officials, 24 trains were delayed by 2-5 hours due to poor visibility.