Some areas have seen more than 40 consecutive days of rain – as fears also grow in North Korea about damage to crops.
At least 30 people are dead and a dozen are missing after more than a week of devastating torrential rain caused landslides and floods in South Korea.
The government said the casualties include 13 dead and two missing from the last two days, as the country battles through its longest monsoon since 2013.
Some areas have seen more than 40 consecutive days of rain.
The downpours left more than 3,700 people displaced on Friday and Saturday alone, like residential areas, roads, and farming fields all experienced devastating flooding.
And the capital city, Seoul, and other southern regions have been warned by the safety ministry that even more heavy downpours are expected on Sunday.
Landslide warnings remain in place at the highest level for every region except the holiday island of Jeju.
Weather official Woo Jin-kyu said most places in South Korea had received three to four times more rainfall last week than the average precipitation recorded in the same period across the last 30 years.
Trapped residents were pictured using rubber rings to stay safe in the southeastern county of Hadong, while cows were seen struggling to keep their heads above water in southwestern Gurye.
Some have also had to be rescued from their cars, having been left stranded by flooding on the roads.
About 100 meters of levee collapsed at the Seomjin River on the southern edge of the Korean peninsula on Saturday, forcing about 1,900 people to be evacuated from the local area.
Five homes were buried in a landslide on Friday from a mountain behind a village in Gokseong, South Jeolla province,
killing five people and requiring more to be rescued.
Forecasters fear the monsoon could end up eclipsing the length of the one seen in 2013, which at 49 days is the country’s longest on record.
North Korea has also been hit by the floods, with concern growing there about damage to crops.
Leader Kim Jong Un visited a town on the border with its southern neighbor on Friday to inspect the damage.
There, torrential rain has destroyed 179 houses and flooded rice-growing land – but there have been no fatalities, according to state news agency KCNA.
North Korea’s ruling party newspaper, Rodong Sinmun, cited a study that said rice and corn would suffer if the crops were underwater for just two or three days.