The National Building Research Organisation has issued landslide warnings for some areas.
The warning was issued initially for the Kalutara and Badulla districts as heavy rains continued to lash most parts of the country.
Meanwhile, the Department of Meteorology said that the prevailing showery conditions are expected to enhance over the island tomorrow.
The Department of Meteorology said that showers or thundershowers will occur at times in most parts of the island tomorrow.
It said that very heavy falls of about 150 mm can be expected at some places in the Central, Uva, Sabaragamuwa, North-western and Western provinces.
Heavy falls about 100 mm can be expected at some places in the North-Central and Southern provinces and in the Mannar, Vauniya districts.