Northern India experienced a deepening winter chill on Thursday, with the fringes of Dal Lake and other water bodies freezing in Jammu and Kashmir. Mercury plunged across the region, including Delhi and Uttar Pradesh. Srinagar recorded its coldest night of the season at minus 5.1°C, while Sonamarg registered minus 9.8°C. Kashmir is currently in the 'Chilla-i-Kalan' period of extreme cold, with dry but cloudy weather expected until January 20.