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Heavy downpour breaks Seosan's rainfall record by more than 100 millimeters

Published: 17 Jul. 2025, 12:20

Roads and houses in Seosan, South Chungcheong, are submerged on July 17 after heavy rain pounded the western coastal area of the province. [YONHAP]

A record-setting downpour swept through Seosan, South Chungcheong, early on Thursday, an event Korea's weather agency says occurs only once in a century. The extreme weather also triggered a brief malfunction in the city’s monitoring system.

In Seosan, more than 400 millimeters (15.7 inches) of rain fell in just half a day. According to the Korea Meteorological Administration (KMA), the city recorded 438.5 millimeters of daily rainfall as of 10 a.m. Thursday, the highest in the country.

It took just 10 hours to break the previous daily record for Seosan, which was 274.5 millimeters on Aug. 2, 1999, adding at least 100 millimeters more.

At around 2:46 a.m., Seosan also logged a new record for hourly rainfall, with 114.9 millimeters falling in a single hour. This surpassed the previous record of 105.4 millimeters set on June 29, 2022. Hourly rainfall of over 110 millimeters is a once-in-a-century occurrence, according to the KMA.

Seosan’s weather monitoring system even experienced a temporary failure at 5 a.m., interrupting rainfall measurements.

“Thunder and lightning continued for three to four hours overnight in the area, and it is presumed that the equipment malfunctioned after being struck by lightning,” a KMA official said. The agency has since restored the data through on-site inspections and is checking nearby automatic weather stations as well.

Heavy rain is forecast to continue across most of the country, with rainfall rates of 30 to 50 millimeters per hour expected. Some southern and central regions, including the southern part of Chungcheong, may see extreme rainfall of 50 to 80 millimeters per hour.

A road in Seosan, South Chungcheong, is submerged early July 17 after heavy rain pounded the western coastal area of the province. [YONHAP]

Heavy rain warnings have been issued for the Chungcheong, Sejong, Gwangju and parts of South Jeolla and South Gyeongsang.

“The band of rain clouds forming over the Yellow Sea and the Chungcheong region will bring strong and sustained rain through Friday morning,” the KMA said. “We urge people to take precautions to prevent damage.”

In the southern regions, the heavy rain is expected to persist through Saturday.

Flood risks are also rising, with rivers threatening to overflow. As of 9 a.m., the Ministry of Environment issued 26 flood alerts, including nine flood warnings and 17 advisories.

“We expect the heavy rain to continue beyond today,” said Vice Environment Minister Kum Han-seung. “We will focus all efforts on preventing flood damage by monitoring river levels and operating dams preemptively.”

Translated from the JoongAng Ilbo using generative AI and edited by Korea JoongAng Daily staff.
BY CHON KWON-PIL [[email protected]]