The concentration of ultrafine dust will be "bad" in the metropolitan area, Chungcheong Provinces, Jeolla Provinces and Daegu.

The levels in the metropolitan area and the entire South Chungcheong region, however, may temporarily rise to "very bad" in some places while the ultrafine dust advisory is in effect.

Starting Friday, the fine dust concentration should gradually ease.

Snow is also forecast in some parts of the nation Thursday, including the Yeongdong region of Gangwon Province, with five to ten centimeters of snow expected in these areas by Friday, while the northeastern region of North Gyeongsang Province will see three to eight centimeters of accumulation.

Friday's morning temperatures will be similar to or slightly higher than Thursday, with temperatures ranging from minus four degrees Celsius to five above across the country, while the daytime readings will range from four to ten degrees nationwide.