Intense rain continues. In Seosan, South Chungcheong Province, rain fell with a strength that occurs once every 200 years. Currently, a "heavy rain warning" is in effect for some areas in Chungcheong, Daejeon, Sejong, Gwangju, North Jeolla, and South Gyeongsang.
Such heavy rainfall is also forecasted for tonight and tomorrow night. On the night of the 17th, about 80 mm of rain per hour is expected in the Chungcheong region, and on the night of the 18th, similar conditions are predicted for Busan and other southern regions. An hourly rainfall of 80 mm is not only difficult for vehicles to operate but also poses a very dangerous level of intense rain that could lead to large-scale disasters.
According to the Korea Meteorological Administration on the 17th, 114.9 mm of rain fell in Seosan from 1:46 a.m. for one hour. This is the highest hourly precipitation recorded since the start of weather observation in Seosan in January 1968. The Korea Meteorological Administration explained that this corresponds to a probability of occurring once every 100 years.
Such rain has continued for an extended period, setting a record for maximum daily precipitation. From midnight to 10:23 a.m. that day, 438.5 mm of rain fell, breaking the previous record of 274.5 mm set on August 2, 1999. According to the Korea Meteorological Administration, this level of intensity is what might be expected once every 200 years.
Nearby Hongseong in South Chungcheong also set a record. In Hongseong, 98.2 mm of rain poured down from 4:22 a.m. for one hour. This is the highest hourly rainfall recorded in the region since weather observation began in November 2015.
The rain that was pouring in the Chungcheong region overnight has now spread across the country as of 10:50 a.m. on the 17th. Currently, "heavy rain warnings" are in effect for Gongju, Nonsan, Geumsan, Buyeo, Seocheon, and Gyeryong in South Chungcheong; Cheongju, Boeun, Goesan, Okcheon, Chungju, Jincheon, Eumseong, and Jeungpyeong in North Chungcheong; Naju and Damyang in South Jeolla; and Hampyeong, Changnyeong, Gwangju, Sejong, and Daejeon. A heavy rain advisory has been issued in parts of Seoul, Jeju, Gyeonggi, Gangwon, South Chungcheong, North Chungcheong, South Jeolla, North Jeolla, North Gyeongsang, and South Gyeongsang. A heavy rain advisory is issued when the predicted rainfall is expected to exceed 60 mm over three hours or 110 mm over 12 hours, and a heavy rain warning is issued when 90 mm or more, or 180 mm or more is expected.
The Korea Meteorological Administration noted, "Strong heavy rain accompanied by gusts and thunder is expected in most parts of the country," and urged caution against flood damage.
Rain is expected to continue until Saturday, the 19th. During this period, extreme rainfall in the form of localized heavy rain is also anticipated. Tonight, rain is expected primarily in the Chungcheong region, while tomorrow night, it will focus on the southern regions.
According to the maximum rainfall intensity predicted by the Korea Meteorological Administration, some areas in South Chungcheong could see more than 80 mm of rain until the afternoon of the 18th, while the southern coast of Jeolla, Busan, and the southern coast of Gyeongnam, as well as around Jirisan, are expected to receive 50–80 mm of rain between early morning on the 18th and the morning of the 19th.
By the night of the 19th, most of the rain will have stopped across the country. After that, a heatwave is forecasted. The Korea Meteorological Administration warned, "With high humidity, the maximum feels-like temperature will rise to around 33 degrees in most parts of the country, making it hot," and advised against going out due to the high likelihood of heat-related illnesses.