Sunday, the 21st, the summer solstice and the longest day of the year, will see many clouds nationwide. In Yeongdong, Gangwon, it will be mostly overcast, with some places seeing rain continue through the morning. The daytime high is expected to be 30 degrees.
According to the Korea Meteorological Administration on the 20th, rain will fall in the Gangwon mountains and along the East Coast through the morning of the 21st, and winds are expected to be very strong through the afternoon. Waves on the East Sea will be very high, topping 5 meters. Expected precipitation is 20–60 millimeters in the northern Gangwon mountains and East Coast, and 5–40 millimeters in the central and southern Gangwon mountains and East Coast.
From dawn to morning, some inland areas of Gyeonggi and Gangwon, the Chungcheong region, the Jeolla region, and inland Gyeongsang may see fog with visibility under 1 kilometer. In particular, fog will be thicker on roads near rivers, lakes, and valleys. Along the East Coast, for the time being, high swells may crash over breakwaters and coastal rocks, so caution is advised to prevent accidents.
Morning lows are expected to be 15–21 degrees, and daytime highs 22–30 degrees. Morning lows in major areas are 19 degrees in Seoul, 19 in Incheon, 18 in Suwon, 17 in Chuncheon, 18 in Gangneung, 18 in Cheongju, 18 in Daejeon, 18 in Jeonju, 19 in Gwangju, 19 in Daegu, 21 in Busan, and 21 in Jeju.
Daytime highs are 29 degrees in Seoul, 28 in Incheon, 29 in Suwon, 29 in Chuncheon, 23 in Gangneung, 29 in Cheongju, 28 in Daejeon, 28 in Jeonju, 30 in Gwangju, 29 in Daegu, 28 in Busan, and 26 in Jeju. Fine dust levels will be at a "moderate" level in all regions.