Why are the delta regions of Eastern India struck by cyclones?
By early November, the low-pressure conditions over North-Western India, get transferred to the Bay of Bengal.
With this shift, there is occurrence of cyclonic depression (originating over the Andaman sea).
These cyclones, after coming under influence of retreating monsoon, cross the Eastern coasts (direction of flow East to West) of India. They cause heavy and widespread rain.
Therefore, the delta regions of Eastern India are struck by cyclone.