On Tuesday the 21st, most of the country will see mostly cloudy to overcast skies, with forecasts calling for torrential downpours of up to 120 mm in the central region.
According to the Korea Meteorological Administration on the 20th, 30–80 mm of rain will fall over the course of the 21st in the capital area, including Seoul, Incheon, and Gyeonggi Province, as well as the five West Sea islands. Some areas will see torrential downpours exceeding 120 mm.
Inland and mountainous areas of Gangwon are also expected to receive 30–80 mm of rainfall, with some parts of the mid- to northern inland areas of Gangwon likely to see as much as 120 mm or more of heavy rain concentrated in a short period.
In addition, the expected rainfall in the Chungcheong region is 30–80 mm. Some parts of the northern Chungnam West Sea coast may see more than 100 mm of monsoon rain. Jeonbuk, Gwangju–Jeonnam, Daegu–Gyeongbuk, and the western inland of Gyeongnam are expected to receive 5–40 mm of rain, while Jeju Island is expected to get around 5 mm.
This rain is expected to pour down intensively from the pre-dawn hours until before noon. In Seoul and the broader capital area and the mid- to northern inland of Gangwon, heavy bands of rain of about 30–50 mm per hour are likely, with about 20–30 mm per hour along the northern Chungnam West Sea coast.
The Korea Meteorological Administration warned that sudden torrential downpours with strong winds, thunder, and lightning could swell rivers or inundate low-lying areas, posing a high risk. It also urged caution, noting that extremely dangerous accidents such as landslides or retaining wall collapses could occur, and asked the public to pay close attention to managing nearby facilities.
The heat wave will continue. Morning lows on the 21st will range from 22 to 26 degrees nationwide, and daytime highs are expected to surge to between 26 and 37 degrees. In Seoul, the morning low will be 25 degrees, and the daytime high will stay around 28 degrees.
Even as the rain continues, abundant atmospheric moisture will push perceived temperatures to around 33 to 35 degrees, especially in parts of the Chungcheong region, the southern provinces, and Jeju Island, where the furnace-like heat will persist.