South Korea's "guerrilla rains" returned on Friday, bringing rainfall of up to 180 mm (7.2 inches) in some areas and wreaking more havoc, officials said.
"The rains are expected to fall from late on Friday, continue on over the weekend and ease off from Monday," said a Korea Meteorological Administration official.
"We believe the rains will not be as damaging as the past weeks, but we should brace ourselves all the same."
South Korean media have dubbed the unpredictable storm fronts during what should be the height of the hot and dry season "the guerrilla rains".
The death toll reached 267 with 73 others missing from the last two weeks of rain, which have also caused damage of at least 700 billion won ($525 million), a figure that has mounted by the day.
Officials held out little hope that many survivors would be found among the missing in the aftermath of one of the worst weather-related disasters South Korea has seen since Typhoon Sarah swept through 30 years ago, killing 850.
Seoul and other northern regions received 70 to 80 percent of their annual average rainfall in the first 10 days of August, the meteorological office said.
The southwestern city of Kwangju was pelted by 120 mm (4.8 inches) on Thursday, a weather official said.
A heavy rain alert was still in place in the region, which was likely to see another 150 mm (six inches) of rain on Friday, the National Disaster Prevention Countermeasures Headquarters said in statement.
The rain-induced disasters have left 150,000 people homeless, damaged or destroyed 1,500 homes and some 3,000 roads and bridges, and washed away some 9,000 graves, the statement said. Three railway lines remain closed.
South Korea was already grappling with a severe economic crisis which has bankrupt businesses, caused mass layoffs and forced the country to accept a financial lifeline from the International Monetary Fund.
Soldiers and workers laboured to clear 140,000 tonnes of trash left behind from the floods while volunteers and Red Cross workers provided food and medical aid to flood victims, the disaster headquarters said.
A central Bank of Korea official said the damage to factories and farmland could cause a sharper contraction in the economy this year than the four percent contraction projected by the government and the IMF.
South Korea's unification ministry has said political rival North Korea has so far not been hit as hard by the rains.
($1 = 1,332 won)