Chillai Kalan is a 40 day period in Kashmir when the winter is at its harshest. It starts on December 21st and ends on January 31st. During this period, the temperature drops so low that all water bodies freezes over and icicles form on surfaces. It is followed by the ‘Chillai Khurd’, meaning ‘small cold’- a 20 day period of cold wave. This is followed by the ‘Chillai Bachha’ or baby cold, a 10 day period.