Up to 528 mm of rain in the central or southern parts of the country over the weekend left 11 people dead, four missing, and 106 households flooded.
Some 97 houses were inundated in Jinju, South Gyeongsang Province and Goheung, South Jeolla Province, 16,444 ha of farmland drenched, and 36 roads destroyed. Jinju saw 318 mm of rain on Saturday alone, a record for July.
Overall more than 30 mm of rain per hour drenched Korea over the weekend as a wet-weather front has been shuttling back and forth from north to south since the monsoon season began on June 22.
This year's rains are unusual, the Korea Meteorological Administration said Sunday. "The monsoon front usually recedes in late July, but we can't predict when it will be over this year. If the heavy downpour keeps up, we could see record rainfall for the season."
Korea saw an average 480.4 mm of rain over the 19 days since June 22, far much than the 20-year average of 357.9 mm between 1981 and 2010. In terms of daily precipitation, this year's 25.3 mm of rain was around 2.3 times the 11.2 mm average in previous years.
The current record for monsoon rainfall is 693.4 mm set in 2006. Next were the 579.4 mm in 1987, 530.7 mm in 2009, and 529.2 mm in 2003. This year already ranks sixth with the amount of rain for the past 19 days alone.
The central part of the country will likely continue under the influence of the monsoon front until Friday, a KMA spokesperson said. It is uncertain whether the front will move northwards to put an end to the rainy season, or advance southwards again to bring more downpours, he added.
Chungju, North Chungcheong Province experienced the most rain in the last 19 days at 763.1 mm as of 3 p.m. on Sunday, or already 62.9 percent of the average annual rainfall of 1,213 mm there in the last three decades.
This year's monsoon front has not reached south of Jeju, the KMA said. With a stronger North Pacific high pressure front than in past years, more vapors collided with the cold, dry air mass in the upper atmosphere, leading to frequent torrential rains.