The Department of Meteorology says the depression over Southwest Bay of Bengal is located 370km to the northeast of Trincomalee.
It is likely to cross Sri Lanka during the next 48 hours.
The Met Department said under the influence of this system, rainy and windy conditions are likely to increase over most parts of the island tomorrow and on Sunday.
It added showers will occur at times in the Northern, Eastern, Uva and North-Central provinces.
Showers or thundershowers can be expected in several places elsewhere during the afternoon or night.
The Met Department said strong gusty winds of about 40-50kmph can be expected at times over the Northern, Eastern, Western, Sabaragamuwa and Uva provinces.
Meanwhile, the general public has been requested to take adequate precautions to minimize damages caused by temporary localized strong winds and lightning during thundershowers.