Nor'westers or the Kalbaishakhi is a local thunderstorm which occurs in India and Bangladesh. Kalbaishakhi occurs, with increasing frequency, from March till monsoon establishes over North-East India. Sometimes it might be progressive derechos. During this time Odisha, West Bengal, Assam, Bihar, Chhattisgarh, Jharkhand, Bangladesh and North-Eastern states of India are affected by violent thunderstorms. They cause considerable damage to life and property and are known as Kalbaisakhi or the calamity of Baishakhi, the month of April–May in India. Kalbaishakhi is accompanied by strong squalls and sometimes by hail. On extremely rare occasions, tornados may also accompany them too. Flying through these winds can be extremely dangerous. Circumnavigating or penetrating them may be disastrous and pilots avoid them. However, the rainfall in these storms is beneficial for the tea cultivated in Assam and for the jute and rice cultivated in West Bengal.