On Wednesday the 15th, early-summer-like weather will continue nationwide, with daytime highs rising to 26 degrees. However, morning temperatures will drop to around 10 degrees, leading to large day-to-night temperature swings.
According to the Korea Meteorological Administration on the 14th, temperatures on the 15th will range from 6–13 degrees in the morning and 14–26 degrees during the day, higher than the seasonal averages (low 3–10 degrees, high 16–21 degrees). In particular, mainly in inland areas, the temperature difference between day and night will widen significantly to around 15 degrees.
Expected morning lows in major cities are 13 degrees in Seoul, 11 in Incheon, 9 in Chuncheon, 10 in Gangneung, 11 in Daejeon, 10 in Daegu, 12 in Jeonju, 12 in Gwangju, 13 in Busan, and 13 in Jeju.
Expected daytime highs are 26 degrees in Seoul, 23 in Incheon, 26 in Chuncheon, 16 in Gangneung, 25 in Daejeon, 24 in Daegu, 24 in Jeonju, 25 in Gwangju, 21 in Busan, and 19 in Jeju.
The country will be mostly cloudy, then gradually clear from the morning. Jeju will see rain between 6 a.m. and noon on the 15th, and parts of the Gyeongnam region and the southern East Sea coast of North Gyeongsang may get raindrops of less than 0.1 mm from dawn to morning. Expected rainfall is 5–10 mm in Jeju, and less than 5 mm along the southern coast of South Jeolla and in Busan and along the southern coast of South Gyeongsang.
The Korean Peninsula will lie on the edge of a high-pressure system moving from northeastern China to the East Sea, while the southern regions and Jeju will gradually move out of the influence of a low-pressure system passing south of Jeju over the sea. Accordingly, most areas nationwide will be cloudy and then clear from the morning, while Jeju will be cloudy and then see intervals of clouds from the afternoon.
Fine dust levels will range from "good" to "moderate" nationwide. However, Incheon may temporarily reach "unhealthy" levels at dawn.