Explanation:

During the hot weather period i.e from March to May the Eastern and North-eastern states of the subcontinent like West Bengal, Bihar, Assam, Odisha (parts) and  Bangladesh experience dramatic appearance of a special type of violent thunderstorm known as Nor’wester. In Bengal it is known as ‘Kal Baisakhi’ or calamity of the month of Baisakh (April,15-May,15). Apart from its destructive effects like sudden rise in wind speed, lightning, thunder and hail the rainfall associated with the storm although small in amount, is extremely helpful for the pre-Kharif crops like jute, paddy, summer till and a large number of vegetables and fruits and the sudden drop in temperature gives relief after unbearable mid-day heat.