'Chillai-Kalan', the harshest 40-day period of winter in Kashmir, marked its beginning today with mercury dipping to the season's record low at several places. Srinagar witnessed a six-year-low night temperature in the month of December and settled at minus 6.5 degrees Celsius. Kashmir Valley and Ladakh region have been hit by severe cold as the night temperature dropped to the season's lowest, except Pahalgam and Gulmarg, said the MeT department official in Srinagar.