Rain will fall nationwide starting on the 24th. In particular, heavy rain will pour down, mainly in western regions. Over the two days of the 24th–25th, more than 100 mm will fall along the Chungnam west coast and in Jeolla.
The Korea meteorological Administration said in an ad-hoc forecast briefing on the 23rd, "Starting Wednesday the 24th, rain will begin across most of the country," and added, "From the afternoon of the 25th, the rain in the central region will gradually weaken, while Jeolla, southern North Gyeongsang, South Gyeongsang, and Jeju Island will see occasional rain through the 26th."
Expected rainfall for the 24th–25th: ▲ Seoul metropolitan area, inland/mountainous Gangwon, inland Chungcheong 20–60 mm (80 mm or more in places) ▲ Chungnam west coast and Jeolla 30–80 mm (100 mm or more along the Chungnam west coast and northwestern North Jeolla/South Jeolla) ▲ Five West Sea Islands 30–80 mm (100 mm or more in places) ▲ South Gyeongsang 20–60 mm ▲ North Gyeongsang 10–40 mm ▲ Jeju 10–60 mm. The northern Gangwon east coast will see 5–20 mm, and the central/southern Gangwon east coast around 5 mm, with relatively less rain.
The rain is expected to pour down intensely. In the central region between the morning and night of the 24th, 20–30 mm per hour is expected, and from early morning to morning on the 25th, 30–50 mm per hour of very heavy rain will fall, centered on the Chungnam west coast and the western part of North Jeolla. Rain is also expected nationwide over the weekend of the 27th–28th.
This rain will be indirectly affected by Typhoon No. 18 "Ragasa" over the southern seas and Typhoon No. 19 "Neoguri" east of Japan. The likelihood of either typhoon approaching or making landfall on the Korean Peninsula is low. However, moisture developed by the typhoons will trigger torrential downpours.
Strong winds and high waves are expected over the South Sea and Jeju waters on the 23rd–24th, and over the West Sea on the 24th. Along the South Coast and Jeju coast, swell waves may overtop breakwaters, so precautions are needed to prevent coastal safety accidents.
Temperatures will see daytime highs around the seasonal average of about 25 C through next week, and due to the influence of rainfall, the lows will be 2–4 C higher than average, narrowing the daily temperature range. From the 24th–28th ahead of the Chuseok holiday, cloudy skies and frequent rain will keep conditions humid, then from Monday the 29th, morning temperatures are expected to drop sharply, turning chilly.