On Tuesday, the 17th, morning temperatures in South Korea are forecasted to drop below freezing, causing a chill across the country, while temperatures during the day are expected to vary significantly by around 15 degrees. According to the Korea Meteorological Administration, regions in the central and southern areas, especially inland areas, may experience frost in the mornings due to the low temperatures. The expected daily temperature highs will range between 12 to 19 degrees Celsius, with specific predictions such as 15 degrees in Seoul and 18 degrees in Gwangju.

In terms of air quality, fine dust levels are projected to reach 'bad' levels in regions including the capital area, Gangwon, and parts of Honam and Yeongnam. While overall conditions may vary, cities like Daegu, Gyeongbuk, and Gyeongnam will likely experience poor air quality throughout much of the day. The meteorological agency has advised residents to pay attention to health management especially because of the large temperature differences between day and night.

As the day progresses, the weather is expected to clear up initially but will gradually become overcast by evening. The situation calls for residents to remain cautious due to the combination of cold weather and air pollution, further emphasizing the importance of staying informed about both weather conditions and health advisories related to air quality.