Naval and fishing communities are advised not to venture into the sea areas as the low-pressure area over south-east Bay of Bengal is likely to move west-north-westwards and become a depression, the Natural Hazards Early Warning Centre of the Meteorology Department in Sri Lanka said.
The depression will reach north Tamil Nadu, Puducherry and adjoining South Andhra Pradesh coasts by tomorrow.
Heavy rainy weather in the southwestern part of the island is expected to reduce gradually.
Showers or thundershowers will occur at times in Northern Province and fairly heavy showers above 50mm are likely at some places.
Several spells of showers will occur in Western, Sabaragamuwa and North-western provinces and in Galle, Matara, Kandy and Nuwara-eliya districts, it said.
Showers or thundershowers will occur at several places elsewhere during the evening or night.