On the 25th, a substitute holiday for Buddha's Birthday and a Monday, the heat will continue but gradually ease with rain and wind. The central region will be mostly sunny before turning increasingly cloudy, while the southern region and Jeju Island will see cloudy skies.
According to the Korea Meteorological Administration on the 25th, early-summer heat will continue across the country, mainly in inland areas. With cloud formation suppressed by subsiding air under high pressure, temperatures will rise sharply, and the gap between daytime and nighttime temperatures will widen.
Daytime highs will range from 22 to 30 degrees, with particularly scorching heat in inland areas such as ▲ Seoul (30 degrees) ▲ Daejeon (29 degrees) ▲ inland Gangwon (30 degrees). The difference between daytime and nighttime temperatures is expected to be around 15 degrees.
From the afternoon, under the influence of a low pressure system from China, rain will begin in Jeju and along the South Coast and expand nationwide on the morning of the 26th. Expected rainfall is ▲ Seoul metropolitan area, Chungcheong region, and Gangwon: 30–80 mm ▲ South Jeolla and South Gyeongsang: 50–100 mm ▲ South Coast of South Jeolla and South Gyeongsang: 80–150 mm ▲ Jeju: 50–150 mm (more than 250 mm in the mountains).
On the 26th, heavy rain will pour all day. Along the South Coast, near Jirisan Mountain, and in Jeju, very heavy rain of around 50 mm per hour may fall. Some areas may also see thunder and lightning with gusty winds.
The Korea Meteorological Administration said, "It appears that the southern region will see heavy rain at a level warranting a heavy rain advisory," and noted, "Extra caution is required for facility management and traffic safety."