The frigid air barrelling through north-India plummeted temperatures to season's lowest in Delhi and neighbouring states on Saturday with many places recording a minimum of below two-degrees Celsius, as dense fog reduced visibility and disrupted air, rail and road traffic. The IMD has issued a red-colour warning for Punjab, Haryana, Delhi, Rajasthan, Uttar Pradesh and Bihar, and amber-colour warning for Madhya Pradesh for Sunday.