The Met Department says that many parts of the island could experience heavy rainfall in the coming few hours.
It said Central, Sabaragamuwa, Uva, Western, and North-Western provinces as well as Amparai, Batticaloa, Galle and Matara districts will experience heavy rainfall exceeding 100mm.
The Irrigation Department announced that one sluice gate of the Udawalawa Reservoir has been opened due to persistent rains.
The people living in the low-lying areas are urged to be vigilant.
Meanwhile, the Disaster Management Center said 6 sluice gates of Daduru Oya reservoir have been opened.
It urged the people living in low lying areas in Chilaw, Pallama, and Arachchikattuwa to be vigilant.