Cold air pushing in from the northwest will send morning temperatures in Seoul down to 5 degrees Celsius on the 22nd, bringing the first cold wave of the autumn to much of South Korea.
Cold wave advisories took effect at 9 p.m. on the 21st across Gyeonggi, Incheon, Gangwon State, the Chungcheong region, parts of North Gyeongsang and South Gyeongsang provinces, parts of Jeonbuk State, as well as Daejeon, Sejong and Gunwi in Daegu, the Korea Meteorological Administration said.
A cold wave advisory is issued when the morning low is forecast to fall at least 10 degrees from the previous day to 3 degrees or below, and to run at least 3 degrees under the seasonal average.
The chill came as a mass of strong cold air moved in from the northwest. Rain that had continued through the morning mostly stopped, but temperatures fell quickly and winds strengthened, making conditions feel far colder.
As of 1 p.m. on the 21st, temperatures stood at 15.2 degrees in Seoul, 14.6 in Incheon, 16 in Suwon, 14.3 in Paju, 16.7 in Daejeon, 17.5 in Sejong, 17.8 in Daegu, 20.8 in Busan, 18 in Gwangju and 19.7 on Jeju.
Daytime highs were also expected to stay around 17 degrees in Seoul and Daejeon and about 20 degrees in Gwangju and Daegu, roughly 2 to 6 degrees below the seasonal average.
Temperatures were forecast to drop more sharply overnight. Morning lows on the 22nd will fall to 5 degrees in Seoul and Daegu and 3 degrees in Daejeon. Some areas in northern Gyeonggi and the inland and mountainous parts of Gangwon State will see readings below freezing.
The Chungcheong region will also cool markedly. Jecheon in North Chungcheong Province was forecast to fall to zero, Eumseong and Goesan to 1 degree, and Chungju, Danyang, Boeun and Yeongdong to 2 degrees. Sejong, Jincheon and Jeungpyeong were expected to reach 3 degrees and Cheongju 5 degrees.
Strong Winds Deepen the Chill; Warmer From Friday Afternoon
Strong winds will make it feel much colder than the actual temperature. Gusts of about 15 meters per second were expected across most of the country, with bursts topping 20 meters per second along the coast and in mountainous areas.
Strong wind advisories were issued for Yeosu in South Jeolla Province and parts of Gangwon State's east coast and mountains, while high seas advisories were in effect for some waters, where waves were expected to reach up to 3.5 meters.
The sudden drop also raises the chance of frost across inland areas nationwide. Water may freeze in eastern Gyeonggi, inland and mountainous Gangwon State, North Chungcheong Province, the northeastern part of Jeonbuk State, and the inland and mountainous areas of north-central North Gyeongsang Province.
The cold spell is not expected to last long. The weather agency said temperatures would gradually rise from the afternoon of the 23rd and return to seasonal norms.
"With temperatures falling more than 10 degrees in a single day, please take care of your health and prepare so that crops do not suffer cold damage," an official at the Korea Meteorological Administration said.