A red-colour warning has been issued for Delhi and neighbouring states for Sunday after the temperature in the national capital dropped to 2.4 degree Celsius and is likely to plunge further. The Indian Meteorological Department also issued the red-colour warning for Punjab, Haryana, Rajasthan, Uttar Pradesh and Bihar. While Saturday was classified as a cold day by IMD, Sunday and Monday will be cold wave days. On Sunday morning, the national capital and adjoining regions remained engulfed in a thick blanket of fog. A red-coded warning is given for extreme weather events.