On Friday, the 20th, South Korea is forecasted to experience mostly mild weather with daytime temperatures exceeding 10 degrees Celsius in most areas. The Korea Meteorological Administration has advised that there can be a temperature difference of more than 15 degrees between day and night, particularly in inland areas, which necessitates caution for health management. While the country will be generally clear, regions like the metropolitan area and Gangwon may experience occasional cloudiness, and a very dry atmosphere is expected, especially in the Gyeongsang region.

Morning temperatures are predicted to range from -7 degrees to 4 degrees Celsius, similar to the average, but daytime highs are expected to rise higher than normal, reaching between 10 to 16 degrees. Specific morning lows are forecasted for major cities such as Seoul (0 degrees), Incheon (1 degree), and Chuncheon (-5 degrees), while afternoon highs are anticipated to be around 13 degrees in Seoul and 16 degrees in Daegu and Jeju. The temperatures are expected to trend even warmer into the next day, with an overall rise to above 15 degrees Celsius expected, potentially leading to safety hazards as ice on rivers and lakes may thaw during the day.

Air quality will also be an issue, with pollution levels expected to be 'bad' in Seoul, northern and southern Gyeonggi, as well as eastern Gangwon due to stagnant atmospheric conditions, while other regions are likely to experience moderate levels. Concerns about increased pollution levels are expected in Incheon and the Chungcheong area during the night, compounded by the dry weather conditions prevalent in the entire country.