Flood warnings issued for three Seoul districts as overnight downpour triggers road closures

Heavy rain that fell across Seoul overnight prompted flood warnings for Gangseo-gu, Eunpyeong-gu and Mapo-gu, while authorities closed the East Seoul Expressway and several other roads to traffic.

The Seoul Metropolitan Government said the flood warnings for the three districts were in effect as of 7:30 a.m. Saturday, following a night of intense rainfall. Yangcheon-gu was placed under a flood watch.

A flood warning is issued when hourly rainfall reaches 50 millimeters or more, or when cumulative rainfall over three hours exceeds 90 millimeters.

A flood watch is triggered when hourly rainfall tops 55 millimeters or when 20 millimeters falls within 15 minutes.

As water levels rose in the early morning hours, the Han River Flood Control Office issued a flood advisory around 4:50 a.m. Saturday for the Neobdae Bridge section of Mokgamcheon stream in Seoul.

The office also notified residents in flood-prone areas to take precautionary measures.

The Korea Forest Service raised its landslide crisis alert to Alert level across the entire Greater Seoul area due to the heavy rain. Eunpyeong-gu issued a landslide advisory, while Dobong-gu issued a preliminary landslide warning.

Mapo-gu banned entry into forested areas and urged residents to watch for early signs of landslides.

Around 5:37 a.m., as water levels in Jungnangcheon stream rose amid the heavy rain warning, authorities closed all lanes of the East Seoul Expressway between Surak Underpass and Seongsu Junction.

Around 6:53 a.m., a vehicle fire broke out inside the Yongma Tunnel in Jungnang-gu, prompting a full closure of the tunnel.

The Seoul Metropolitan Government said it had received 120 rain-related complaints and reports, including 89 drainage support requests, four cases of fallen trees and 27 facility safety incidents.

As of 7:30 a.m. Saturday, 29 streams within Seoul were closed, along with four roads — the underpass below Jeungsan Bridge, the underpass below Haengju 1 Bridge, the East Seoul Expressway and Garamgil. Twenty rainwater pumping stations were operating at partial capacity as part of flood-control operations.

The city issued directives to all departments and affiliated agencies to tighten safety management in response to the heavy rain, and relayed the same instructions via text message and SNS.

After the heavy rain warning was issued, the city activated Level 2 emergency operations from 3:40 a.m. Saturday, mobilizing 6,642 city and district civil servants for emergency duty.

Officials stepped up monitoring of vulnerable areas and facilities — including streams, low-lying zones and storm drains — and maintained contact networks with care workers and community support partners.

The Korea Meteorological Administration issued a heavy rain advisory for all of Seoul at 1 a.m. Saturday, then upgraded it to a heavy rain warning starting with the southwestern and northwestern parts of the city at 3:40 a.m., before lifting it at 7:30 a.m.

A heavy rain advisory is issued when three-hour rainfall is expected to reach 60 millimeters or more, or 12-hour rainfall 110 millimeters or more. The thresholds for a heavy rain warning are 90 millimeters over three hours or 180 millimeters over 12 hours.

Of all areas in Seoul, Eunpyeong-gu recorded the highest rainfall between Friday and Saturday, with a cumulative total of 166.0 millimeters.

Seodaemun-gu saw the most intense burst, with rainfall peaking at 64.5 millimeters per hour.

Rain is forecast to continue in Seoul through Sunday. Total expected rainfall from Friday through the three-day period is 100 to 200 millimeters, with some areas forecast to receive more than 300 millimeters.

"We will maintain our situation management and emergency response systems in response to the heavy rain and respond thoroughly," the Seoul Metropolitan Government said.