This file photo from last Tuesday shows central Seoul covered with fine dust. (Yonhap)

Fine dust will rise to "very bad" levels in South Korea's central region, including the greater Seoul area, on Wednesday morning due to the influx of yellow dust originating from deserts in northern China and Mongolia, the state weather agency said.

The density of fine dust particles smaller than 10 micrometers in diameter, known as PM 10, will reach "bad" levels in the eastern Gangwon Province and most of the southern region, including Jeju Island, according to the Korea Meteorological Administration (KMA).

The KMA categorizes concentrations of PM 10 between 81 and 150 micrograms as "bad" and more than 151 as "very bad."

The morning temperatures were 14.5 degrees Celsius in Seoul, 13.8 C in Incheon, 13.9 C in Daejeon, 17 C in Gwangju and 18.1 C in Busan, as of 8 a.m.

The mercury is expected to climb to between 16 C and 25 C across the country in the afternoon, according to the KMA. (Yonhap)