On Friday the 13th, morning temperatures will be below freezing and it will be chilly, with rain or snow in some areas.
In the afternoon, there will be places with rain or snow along the Gangwon east coast and in the mountains, along the North Gyeongsang east coast and northeastern mountains, and in the inland eastern parts of Busan, Ulsan and South Gyeongsang.
Expected snowfall over the two days of the 12th and 13th is 5–15 centimeters in the Gangwon mountains (more than 20 centimeters in some places), 1–3 centimeters on the Gangwon east coast, 1–5 centimeters in the northeastern mountains of North Gyeongsang, and less than 1 centimeter along the northern North Gyeongsang east coast and in Ulsan.
Expected precipitation is 5–20 millimeters along the Gangwon east coast and in the mountains, and along the North Gyeongsang east coast and northeastern mountains, and 5–10 millimeters in Busan and Ulsan.
The central region will be mostly clear, turning mostly cloudy from the afternoon, while the southern region and Jeju Island will see intervals of many clouds.
The east coast region will see mostly cloudy weather.
Morning lows are forecast at -2 to 4 degrees, with afternoon highs at 6 to 14 degrees.
Morning lows in major areas are forecast at Seoul 2 degrees, Incheon 2 degrees, Suwon 2 degrees, Chuncheon -1 degree, Gangneung 3 degrees, Cheongju 1 degree, Daejeon 1 degree, Jeonju 0 degrees, Gwangju Metropolitan City 1 degree, Daegu 2 degrees, Busan 4 degrees, and Jeju 7 degrees.
Afternoon highs are forecast at Seoul 12 degrees, Incheon 11 degrees, Suwon 12 degrees, Chuncheon 11 degrees, Gangneung 7 degrees, Cheongju 12 degrees, Daejeon 12 degrees, Jeonju 12 degrees, Gwangju Metropolitan City 14 degrees, Daegu 12 degrees, Busan 11 degrees, and Jeju 12 degrees.
Fine dust levels are expected to range from "good" to "moderate" in all regions. However, Honam and Jeju are expected to see "bad" levels temporarily at dawn.
Waves will run 1.0–3.5 meters off the east coast, 0.5–1.0 meters off the west coast, and 0.5–2.5 meters off the south coast. In the inner offshore waters (the open sea within about 200 kilometers from the shoreline), wave heights are expected at 1.0–3.5 meters in the East and South Seas, and 0.5–1.5 meters in the West Sea.