1. The most severe part of the winter in Kashmir consists of three months. It is divided into three parts called the Chilas:- The ‘Chillai Kalan’, the ‘Chillai Khurd’, and the ‘Challai Bache’.
2.Chillai-Kalan is a 40-day period of harsh winter. ‘Chillai-Kalan’ begins on December 21 and ends on January 31 of the next year.
3. ‘Chillai-Kalan’ is followed by a 20-day long ‘Chillai-Khurd’ (small cold) that occurs between January 31 and February 19 and a 10-day long ‘Chillai-Bachha’ (baby cold) which is from February 20 to March 2.
4.Interestingly according to Persian tradition, the night of 21st December is celebrated as ‘Shab-e Yalda’ (Night of Birth), or ‘Shab-e Chelleh'(Night of Forty). Iranian Azerbaijanis call it ‘Chilla Gejasi’, which marks the beginning of the first 40 days of winter. The Iranian concept also survives in Kashmir, where Chillai Kalan designates the 40-day harshest winter period.
5.During ‘Chillai-Kalan’, the weather in Kashmir valley continues to remain dry and cold with minimum temperatures hovering below the freezing point.
6.The chances of snowfall are most frequent and maximum in ‘Chillai-Kalan’.
7.The snow during this 40-day period freezes and lasts longer.
8.It is this snow that adds to the glaciers of the Valley and replenishes the perennial reservoirs that feed the rivers, streams, and lakes in Kashmir during the months of summer. Any snowfall after the ‘Chillai Kalan’ does not last long.
9.It mostly remains overcast during this period and even if the sun breaks loose of the cloud cover, it is feeble and helpless against the bone-chilling power of ‘Chillai Kalan’.
Snow-clad mountains in Kashmir During ‘Chillai Kalan‘.
10. In the past, many families would prepare ‘Shebdeg’ on the first day of ‘Chillai Kalan’. A fat duck would be cooked with turnips and spices in an earthen vessel during the night intervening Dec 20-21.