Coastal Tamil Nadu and Puducherry are likely to witness moderate to heavy rainfall beginning early next week, according to the weather department. Light to moderate rain is likely to occur at isolated places over Tamil Nadu between Tuesday and Friday, it said. According to the Indian Meteorological Department, Chennai, a low-pressure area is likely to develop over Indian Ocean and Bay of Bengal and move towards the coastal region in Tamil Nadu intensifying into a storm. "A low-pressure area is very likely to develop over Equatorial Indian Ocean and adjoining South-West Bay of Bengal around 25 April. It is very likely to intensify into a depression by 27 April and move towards Tamil Nadu coast and intensify into a cyclonic storm by 29 April," said Met department official. "Due to this cyclonic activity, moderate to heavy rain likely to occur over coastal Tamil Nadu and Puducherry on 29th .