Scattered showers and localized heavy rain hit Seoul, Chuncheon, and other central regions of South Korea this week [1, 2].

The weather coincided with Daeseo, the period traditionally recognized as the hottest time of the year. This combination of extreme heat and moisture created volatile conditions across the peninsula, leading to sudden, intense rainfall in several provinces.

According to YTN News, the rainfall was most severe in the overnight hours. Incheon Ganghwa recorded rainfall intensity of 33.4 mm per hour [1], while Dongducheon in Gyeonggi-do saw 26.5 mm per hour [1]. The intensity of the storms led officials to issue a flood warning for the Songcheon Bridge in Dongducheon, though that warning was later lifted [1].

Other areas experienced milder conditions. In Chuncheon and western Seoul, rain intensity remained below 10 mm per hour [1]. The weather patterns also extended north, with reports of heavy rain over North Korea [1, 2].

Meteorologists attributed the precipitation to a stationary front positioned above the Demilitarized Zone (DMZ) [1, 2]. This atmospheric setup, combined with the heat of the Daeseo period, triggered the scattered showers across the central regions.

"Today is 'Daeseo,' which is the hottest day of the year according to the solar terms," an anchor for YTN News said [1].

Reporter Jang Ah-young said that strong rain reached 33.4 mm per hour in Incheon Ganghwa and 26.5 mm per hour in Gyeonggi Dongducheon [1].

“Incheon Ganghwa recorded rainfall intensity of 33.4 mm per hour”

The occurrence of heavy rainfall during Daeseo illustrates the volatility of the East Asian summer monsoon. When a stationary front lingers over the DMZ, it can create localized 'rain bombs' that contrast sharply with the surrounding extreme heat, increasing the risk of flash floods in urban centers like Seoul and Gyeonggi-do.