Port Blair: The India Meteorological Department (IMD) has issued a 'cyclone alert' in Andaman and Nicobar Islands due to a cyclonic circulation over the Bay of Bengal, which is likely to intensify from October 21, officials said on Monday. Local port warnings have been issued in the wake of the weather system, which is likely to cause heavy rainfall till October 23, they said. "Heavy rain (7-11 cm) is very likely to occur at one or two places over Nicobar Islands. Thunderstorms with gusty wind (40-50 kmph) and lightning are very likely to occur at one or two places over Andaman and Nicobar Islands on October 21, 22 and 23," an official said. Thunderstorms with gusty wind (40-50 kmph) and lightning are very likely to occur at one or two places over Andaman and Nicobar Islands on October 24 and 25, he said. "Squally weather with surface wind speed reaching 35-45 kmph gusting to 55 kmph is very likely over the Andaman Sea from October 22 to 23. In the coming five days, sea conditions are likely to be rough and fishermen have been advised not to venture into the sea along and off the Andaman Sea and Andaman and Nicobar coast till October 24," he said. Due to the possibility of surging waves, boat owners, Islanders and tourists have been advised by the administration to ply their boats with utmost vigilance, and recreation activities have to be carried out with due care. Tourists and general public were advised not to venture into the sea and requested to follow all safety guidelines issued by the local administration.