Large diurnal temperature range on the first day of October with dense morning fog... daytime highs of 24–29°C

Cloudy on National Foundation Day with rain in Chungcheong and southern regions... rough seas expected around Jeju

Autumn arriving at Seoraksan National Park (Sokcho=Yonhap News) The area around Jungcheong in Seoraksan National Park, Gangwon Province, is gradually turning into autumn colors on the 30th. 2025.9.30 [Provided by Seoraksan National Park Office. Redistribution and DB prohibited] yangdoo@yna.co.kr

On the first day of October, the daily temperature range will be as wide as 10 degrees, centered on inland areas, and dense fog is expected in many places during the morning commute.

The morning low temperature on October 1st is expected to be between 13–19°C, and the daytime high between 24–29°C.

The forecast low and high temperatures for major cities are: Seoul 17°C and 26°C; Incheon 18°C and 24°C; Daejeon and Gwangju 15°C and 27°C; Daegu 17°C and 28°C; Ulsan 16°C and 27°C; and Busan 19°C and 28°C.

Under the influence of a high-pressure system moving east from the West Sea, the entire country will be clear. As a result, active radiational cooling overnight will cause temperatures to drop significantly, leading to chilly mornings, followed by a sharp rise in temperature during the day under bright sunshine.

Consequently, the diurnal temperature range in inland areas is expected to reach around 10 degrees.

As temperatures drop overnight, fog will form in the morning.

From dawn to morning on the 1st, fog with visibility of less than 200 meters is expected in inland areas nationwide (excluding Seoul), as well as in southern Gyeonggi, the west coast of South Chungcheong, and the mountainous regions of Gangwon. Other regions will experience fog with visibility of less than 1 km.

About 5mm of rain is expected in northern Gyeonggi in the late afternoon.

Meanwhile, on the 3rd, when the holiday begins for National Foundation Day, the weather will be cloudy nationwide, with rain falling from dawn to evening in the Chungcheong, southern, and Jeju regions.

Furthermore, starting from the 3rd, winds will gradually strengthen to 25–60 km/h (8–16 m/s) and waves will rise to heights of 1.0–3.5 meters in the far waters of the southern West Sea, the far waters of the South Sea, the Jeju sea area, and the far southern waters of the eastern South Sea.

As ferry schedules for travelers may be disrupted, please check sailing information in advance. Yonhap News