"The cyclonic storm ROANU would move north east wards along and off West Bengal coast and cross Bangladesh coast between Khepupara and Cox's Bazar on 21st (May) night/22nd (May) early morning May," the Met department said in a cyclone warning for West Bengal.
Fishermen have been advised not to venture into the sea.
Officials said heavy to very heavy rainfall is likely in most places over coastal Gangetic West Bengal during the next 48 hours.
Squally wind speed reaching 50-60 kmph gusting to 70 kmph is likely to prevail along and off West Bengal coast.