The Department of Meteorology said rains were expected to increase in the next two days.
It said the rains would be accompanied by lightning in Uva, Sabaragamuwa, Central and Southern Provinces.
The Met Department said fairly heavy rains of up to 75 mm could be expected at some places in Sabaragamuwa, Central, Uva Provinces and in the Kurunagala, Galle and Matara districts.
The public are kindly requested to take adequate precautions to minimize damage caused by lightning.
The Met Department said showers or thundershowers would occur in the sea areas off the coast extending from Hambanthota to Mullaitivu via Potuvil and Trincomalee while showers or thundershowers might occur at several places in the sea areas off the coast extending from Colombo to Matara via Galle in the evening or night. (Sheain Fernandopulle)