Starting next week, temperatures will drop below 10 degrees, making it very chilly. As temperatures fall, some areas may see the first frost, and places such as the Gangwon mountains could even observe the first snow.
The Korea meteorological Administration said at a regular forecast briefing on the 16th, "On the morning of the 20th, most areas nationwide will see temperatures below 10 degrees," adding, "This could be the lowest temperature of this fall." By the latter half of the week, temperatures will rise slightly and return to seasonal norms.
This is due to cold air moving in from the north. Until recently, even as cold northern air periodically moved southward, high pressure over the south held firm, bringing frequent rain to the Korean Peninsula located in between. But after Saturday, the 18th, cold air from the northwest is expected to expand its influence and bring down temperatures.
On top of that, with clear skies and no clouds continuing, the "radiative cooling" effect that efficiently releases heat will add up, causing temperatures to plunge around the 20th–21st. In particular, Seoul could drop to 6 degrees on the 20th. However, the southern regions such as Busan, where temperatures are relatively higher, and Jeju will be near seasonal levels.
As temperatures drop sharply, some areas are likely to see the first frost and the first snow of the year. An official at the Korea meteorological Administration said, "Rain is expected along the East Coast through the morning of the 20th," adding, "At that time, in high mountain areas of Gangwon, the rain could turn to snow, bringing the first snowfall."
Meanwhile, the rain is expected to continue into the weekend. On Friday night, the 17th, light precipitation will begin from the west, and by Saturday, the 18th, the rain will expand nationwide. The Korea meteorological Administration said, "Up to 50 mm of rain is expected along the West Sea coasts of northern Jeolla and South Chungcheong, and people in the Chungcheong and southern regions should watch out for thunder and lightning," adding, "Along the East Coast, the rain will continue through the morning of Sunday, the 19th."
Strong winds will also require caution. The Korea meteorological Administration said, "After the 18th, winds will strengthen, with the possibility of a high wind advisory along the West Sea coast and a high seas warning over all waters," adding, "In the South Sea, this pattern could continue through the 24th, so fishing operations should take care and aquaculture should prepare in advance."
Next week will bring different weather by region. It will be mostly clear and chilly in central and western areas, but the Gangwon Yeongdong and northern Gyeongbuk East Coast regions will see frequent rain. Jeju Island will have mostly cloudy weather.