The Disaster Management Centre (DMC) said the adverse weather condition had left 112 people injured and nearly 6,00,000 people have been forced from their homes, with thousands suffering structural damage from flood inundation and landslides.
The weather has begun to clear, and many of the more than 1.00,000 people who evacuated over the weekend had returned home to begin clearing debris and mud from their waterlogged homes. More than 80,000 others remained in relief camps as their homes were either destroyed or remain unreachable.
The Indian contingent of more than 300 navy personnel was assisting in the relief, with divers searching the brackish waters and medical teams seeing patients in makeshift tents set up at shelters.
INS Shardul has nearly 200 personnel on board, including specialised rescue, diving and medical teams, as well as a large amount of relief material and Gemini inflatable boats.
INS 'Kirch' was carrying 125 personnel. It had diving teams, relief supplies, inflatable gemini boats and a mobile medical team.
A third Indian naval ship arrived today, bringing relief supplies including rice, lentils, sugar, milk and blankets for the displaced.
"Secy to President of SL and SL Navy chief receiving symbolically the relief material on board the 3rd relief and rescue ship INS Jalashwa," the High Commission of India in Colombo tweeted.
Lankan army trucks carried drinking water and food for those affected. Helicopters ferried medicine, relief supplies and inflatable boats to remote areas, while small vessels plied the floodwaters in search of people needing rescue.
Lankan Cabinet spokesman Rajitha Senaratne said that foreign assistance is continuing to flow in with India, China and Pakistan among the countries sending ship loads of humanitarian aid.
The disaster is described as one of the worst-ever calamities since the 2003 floods.
The official death toll was at 193, with another 94 people listed as missing, the Colombo Gazette reported.
The MeT Department in its weather forecast said the cyclonic storm MORA is expected to get weakened when it enters the Bangladesh land and the possibility for heavy rain and strong winds will be reduced by tomorrow.
However, under its influence cloudy skies, windy and showery conditions are expected over the country.
The MeT Department warned that the sea area off the coast extending from Puttalam to Trincomalee via Kankasanthurai and sea area off the coast extending from Galle to Batticaloa via Hambantota can be very rough at times as the wind speed can increase up to 70-80 kmph.
State television broadcast called for public assistance to clean drinking wells contaminated by the monsoon floods.
Lanka's water supply minister Rauf Hakeem said 40 per cent of those affected did not have access to piped drinking water, and there was an urgent need to clean contaminated wells in flood-affected areas.
"Our workers have volunteered to join a major clean up," the minister told reporters in Colombo, adding water distribution stations had also been flooded, disrupting the piped supply.
In total, 5,45,243 people of 1,42,811 families had been affected by the weather calamity. The South-West monsoon unleashed torrential rains, which ravaged fourteen districts in the western and southern parts of the country on Friday and Thursday.
The DMC had issued an urgent evacuation warning last evening instructing residents living along the Kelani River and within the Divisional Secretariats of Kollonnawa, Kaduwela, Wellampitiya, Kelaniya, Biyagama, Sedawatte, Dompe, Hanwella, Padukka and Avissawella to move to safer areas.
The DMC said the residents of Meethotamulla were already evacuated.
It said water levels in the Kelani River were rising rapidly as indicted by the water gauges at Nagalagam Street, Hanwella and Glencourse and warned residents to move away from the vulnerable area as it was under an imminent flood threat.
Those living along the banks of Nilwala Ganga, The Gin Ganga and Kalu Ganga were also asked to move to safer areas because of the rising water levels.
Meanwhile, the DMC requested the people to be vigilant on rising water levels.
"Showers or thundershowers will occur at times in the Western, Sabaragamuwa, Southern, Central and North-western provinces. Heavy falls (about 150 mm) can be expected at some places," it said.
Charities have warned on Monday that thousands of people affected by the floods and landslides are at risk of potentially fatal diseases such as dengue fever, as the death toll from the disaster continued to rise.
Sri Lanka had sought international assistance, with India sending two naval ships laden with supplies over the weekend.
Following India's lead in sending out emergency relief to Sri Lanka, more countries have started pledging assistance to provide relief to the flood victims.