For coastal stations the threshold value of minimum temperature of 10 deg C is rarely reached. However, the local people feel discomfort due to wind chill factor which reduces the minimum temperature by a few degrees depending upon the wind speed. The "Cold Day" concept may be used following the criteria given below:

i) Actual minimum temperature of a station be reduced to WCTn.

ii) This WCTn should be used to declare "Cold Wave" or "Cold Day".

iii) When minimum temperature departure is -5 deg C or less over a station, "Cold Day" may be described irrespective of threshold value of 10 deg C .

iv) However, when a threshold of 10 deg C is reached "Cold Wave" be declared.

v) When a station satisfies both the Cold Wave and Cold Day criteria, then Cold Wave has a higher priority and has to be declared.

Heat wave/ Cold Wave and hot Day/ Cold Day are area specific phenomena. Therefore they may be described for a Met. Sub-division or a part thereof, when at least two stations satisfy the criteria