Floods and landslides in Sri Lanka's southern and western regions have killed at least 120 people and damaged more than 800 homes, officials said on Saturday.
Ninety-one people were also reported missing and 40 others have been hospitalised after unusually heavy rain on Friday triggered a string of mudslides and caused rivers to burst their banks, according to the country's Disaster Management Centre (DMC).
Indian medical teams and emergency relief arrived in the capital, Colombo, on Saturday to help Sri Lanka deal with the worst flooding in 14 years.
Many thousands are displaced and are trying to come to terms with what has happened with this huge deluge of water.
Some places received a year's supply of rain in 24 hours. It has taken everyone by surprise.
100km south of Colombo, rescuers pulled at least 11 bodies out from the mud and earth, while one person was found alive.
It's been 15-18 years since we've had so much water. It's left people helpless, a man told local media.
We were moving things from 2am. Kitchen stuff floated off, and the roof shades were blown away, a woman said.
Authorities issued fresh evacuation orders for those living downstream of two major rivers, citing a risk of flooding even though the rains had subsided.
Soldiers have fanned out in boats and helicopters to help with rescue operations. Residents said there are more people trapped in interior villages where boats have been unable to reach.
An Indian ship carrying medical supplies docked in Colombo on Saturday, after Sri Lanka issued an international appeal for help. Another ship is due to arrive on Monday.
The flooding is the worst since May 2003 when 250 people were killed and 10,000 homes destroyed after a similarly powerful Southwest monsoon, officials said.
The DMC said the monsoon ended a prolonged drought that had threatened agriculture as well as hydropower generation.
Mudslides have become common during the monsoon season in the tropical Indian Ocean island as land has been heavily deforested to grow export crops such as tea and rubber.
Last May, a massive landslide killed more than 100 people in central Sri Lanka.
As Indian medical and emergency teams arrive in Sri Lanka to aid rescue and recovery efforts after devastating floods and landslides, the torrential rains of the past several days are easing.
A large island in the Indian Ocean immediately south of India, Sri Lanka consists of extensive lowland regions around the coast and a large mountainous interior, where the highest peaks rise to more than 2,400 metres.
Situated between six degrees and 10 degrees north, Sri Lanka has a typical tropical climate, which is somewhat modified by the seasonal wind reversal of the southwest monsoon.
Most of the country has an abundant or moderate rainfall which is well distributed throughout the year. The southwest coast and mountain slopes are the wettest regions, with the greatest rainfall during the months of April to June and October to November.
The flooding rains of the past few days were heaviest in the southwest of the country and mainly due to the onset of the southwest monsoon, which typically arrives in Sri Lanka in late May.
One city impacted by flood waters and landslides is Galle, in the country's southwest. In just 24 hours, the city received 163 mm of rain, a quarter of the May monthly average of 718 mm.
In Ratnapura, which is situated in the south-central region of the country, residents received 304mm in just 24 hours, more than half their May monthly average of 520mm.
In Colombo, the country’s capital situated on the west coast, the rains have been considerably less, with 58mm in 48 hours, against a monthly average of 371mm.
Whilst the rain over the past several days has been persistent and heavy across much of the southern half of Sri Lanka, it is that, along with an already saturated ground and high river levels, that has led to this widespread flooding.
Sri Lanka has been seeing the effects of the pre-monsoon showers for almost the entire month of May.
As the rainfall pours down the high peaks from the mountainous interior, it eventually fills the rivers with nowhere else to go, flooding the land at lower levels and bringing down the mud and rocks along with it.
The forecast for the next few days is for less rain than this past week.
Yet, as the southwest monsoon continues to progress northwards into India, the coming months through July are likely to bring enhanced amounts of rainfall, where, once again, the danger of flooding and landslides remains high.