Temperatures drop below freezing across most of South Korea on first day of winter

Morning temperatures dropped below freezing across most inland areas of South Korea on Saturday, the traditional solar term known as Ipdong, or the start of winter. Seoul and Incheon recorded their first ice of the year.

As of 7 a.m., the lowest temperatures recorded were -9.0 C at Seoraksan, -6.8 C at Hoengseong (Dunnae), and -6.6 C at both Hongcheon (Seoseok) and Paju (Panmunjeom), according to Yonhap.

Within Seoul, several districts also saw below-freezing morning lows, including Eunpyeong at -3.3 C, Nowon at -3.0 C, Gwanak at -0.7 C and Seodaemun at -0.1 C.

First ice was observed at multiple inland locations.

The ice formed in small, dish-shaped evaporation pans — 20 centimeters in diameter — placed at outdoor observation sites. The pans are used to measure water evaporation rates.

Seoul's first ice came 10 days later than last year and four days later than the climatological average for 1991–2020. Incheon's came four days later than last year but two days earlier than the average. Daejeon was four days behind both last year and the average.

Clear skies brought by high pressure will allow temperatures to rise during the day, though afternoon highs are expected to remain at 8–13 C, below the seasonal average of 14–19 C.

Strong gusts of around 55 kilometers per hour — up to 70 km/h in mountainous areas — are forecast through the morning, mainly along the eastern coast and Jeju.

Cold air flowing in from the northwest is expected to keep conditions chilly for now. Sunday's morning lows are forecast at -1 to 7 C, with afternoon highs at 7–15 C.

The Greater Seoul area and Gangwon Province's eastern coast are currently experiencing dry atmospheric conditions, with effective humidity as low as 30–40 percent in some areas. Effective humidity measures how dry vegetation such as trees has become; levels below 50 percent significantly raise the risk of large fires.

However, rain expected in central regions Sunday should provide some relief from the dryness.

Rain is forecast to begin Sunday morning in northern Gyeonggi Province and central and northern Gangwon Province, spreading to the Greater Seoul area and the rest of Gangwon Province by late afternoon before tapering off late at night. Some parts of northern Chungcheong Province may also see rain Sunday night.

Rainfall totals are expected to be light, at around 5 millimeters or less.

Meanwhile, the Korea Meteorological Administration has forecast that an El Niño that began in May could become the strongest on record this winter. El Niño is declared when the three-month moving average of sea surface temperatures in the El Niño–La Niña monitoring zone of the tropical Pacific remains at least 0.5 degrees above normal for five or more consecutive months, with the onset dated to the first such month.