A severe cold snap is expected on the 20th with Daehan, the coldest solar term.
Starting on the night of the 19th, cold air will move in from the north, sending temperatures sharply lower. Cold wave advisories have been issued for most regions nationwide except the east coast, Jeolla South and Gyeongsang South, and Jeju, and cold wave warnings have been issued for most of northeastern Gyeonggi and the Yeongseo area of Gangwon. A cold wave warning is issued when the morning low is expected to stay at or below -15 C for at least two days.
On the morning of the 20th, morning lows in central regions will be below -10 C, and will drop to around -15 C in inland northern Gyeonggi and the inland and mountainous areas of Gangwon. Southern regions are also forecast at -10 to -5 C. Compared with the morning of the 19th, temperatures will be about 10 degrees lower nationwide and around 15 degrees lower in eastern Gyeonggi and the inland and mountainous areas of Gangwon. Morning lows nationwide are expected to range from -17 C to -2 C.
Afternoon highs will stay between -4 and 7 C. Central regions and Honam are not expected to rise above freezing even during the day. Forecast temperatures by major city are Seoul -13 to -3 C, Incheon -14 to -4 C, Daejeon -11 to 0 C, Gwangju -6 to 2 C, Daegu -7 to 4 C, Ulsan -5 to 5 C, and Busan -2 to 7 C.
With strong winds forecast, the cold will feel even harsher. In Seoul, the morning low is forecast at -13 C, but the wind chill is expected to drop to -18 C.
On the Chungnam west coast and Jeonbuk west coast, where high wind advisories are in effect, strong winds with instantaneous speeds of 70 kph (20 m/s) or more will continue through the morning of the 20th; on the Jeonnam coast through the night of the 20th; and on Jeju (excluding the southern coast) for the time being. There is also a possibility that high wind advisories will be issued for the Gyeongsang coast starting the night of the 19th. In other regions, strong winds with instantaneous speeds around 55 kph (15 m/s) are expected through the 20th.
This cold snap is expected to last about a week. In Seoul, mornings with lows below -10 C are forecast to continue through the 25th. Nationwide, on the morning of the 21st, lows will be -17 to -4 C with afternoon highs of -7 to 3 C, and on the 22nd, morning lows will fall further to -19 to -5 C with afternoon highs of -7 to -3 C.
With the severe cold persisting, there is a possibility of cold wave damage such as burst pipes. With dry air and strong winds centered on the Yeongnam region east of the Baekdudaegan, there is also a risk of wildfires. A dry advisory is currently in effect for Busan and Ulsan, and the east coasts of Daegu and North Gyeongsang.
Rough conditions are also expected at sea. Starting on the 20th, long-period swells will move into the east coast, and high waves may sweep over breakwaters and rocky shores. In the central West Sea nearshore waters on the morning of the 20th, the central West Sea offshore waters on the afternoon of the 20th, and the southern West Sea nearshore waters from the night of the 20th, winds will blow strongly at 30 to 65 kph (9 to 18 m/s) with waves of 1.5 to 4.0 meters; in the far West Sea and far southern waters off Jeju, waves will reach 5.0 meters or higher.