Unprecedented rainfall has triggered severe flooding and a deadly landslide along South Korea’s southern coast, with more than 800 mm (31.5 in) falling around Geoje during a relentless three-day deluge.
Geoje in South Gyeongsang Province recorded 805.7 mm (31.7 in) of rain from Saturday through 8 a.m. Monday, August 17. Nearby Tongyeong received 671.9 mm (26.5 in), while rainfall rates locally approached 100 mm (3.9 in) per hour.
The enormous rainfall totals caused rivers and streams to overflow and left hillsides dangerously saturated. Early Monday, a landslide struck an apartment building in Geoje, killing at least one person.
The Korea Meteorological Administration maintained heavy-rain warnings across parts of the southern coast as the event continued.
This morning, at least one person has died after flash flooding and a landslide struck Jangpyeong-dong, Geoje-si, Gyeongsangnam-do, South Korea.(August 17) pic.twitter.com/wcccL2GRhi
— Weather Monitor (@WeatherMonitors) August 17, 2026
Several meteorological ingredients combined to produce the exceptional rainfall.
A deeply moisture-rich atmosphere has been feeding humid air toward South Korea’s southern coastline. Low-level convergence near the coast repeatedly forced this air upward, allowing powerful rain-producing clouds to regenerate over similar locations.
Rather than a single rain band quickly crossing the region, successive areas of intense precipitation repeatedly affected Geoje and Tongyeong. This repeated development allowed rainfall totals to accumulate rapidly over several days.
Heavy flooding due to torrential rain in Geoje, South Gyeongsang Province, South Korea 🇰🇷pic.twitter.com/IHcI0tp8Qf
— Disaster News (@Top_Disaster) August 17, 2026
South Gyeongsang’s terrain further amplified the precipitation.
Moist air arriving from the sea encounters hills and mountains close to the coastline and is forced upward. As the air rises, it cools and condenses, enhancing precipitation through orographic lift.
Combined with rainfall rates approaching 100 mm (3.9 in) per hour, this terrain enhancement helped produce extraordinary accumulations across a relatively localized section of the southern coast.
Landslide Risk Remains High
Even as the heaviest rainfall begins to ease, landslides remain a serious concern.
After more than 800 mm (31.5 in) of rain, soils around Geoje are exceptionally saturated. Water infiltrating soil and weathered rock increases pore-water pressure and reduces slope stability, making steep terrain increasingly vulnerable to failure.
Additional rainfall does not need to match the intensity of the earlier storms to trigger further landslides.
The combination of exceptional atmospheric moisture, repeated convective development and terrain-enhanced rainfall has therefore transformed this episode from an extreme rainfall event into a prolonged flood and landslide threat along South Korea’s southern coast.
