It means a type of windy storm from the northwest. Literally 'kal' means "terrible," and 'baishakhi' refers to "something that happens in the month of Baishakh," that falls in the midtime of April. "KalBaishakhi" is a local term mainly used by the people of Bengal, Assam, and Odia. Its literal translation in English language is 'Northwesterlies' or 'Nor'wester'.
Although KalBaishakhi is a strong windy storm, many local people are benefited by it in their farming.