China's meteorological authority on Saturday evening issued a yellow alert for heavy fog in northern and central regions.
Hebei, Henan, Shandong, and Hubei provinces will see heavy fog from Saturday evening to Sunday, with visibility of less than one kilometer in some areas, the National Meteorological Center (NMC) forecast.
South Hebei and north Henan will experience visibility of less than 500 meters, in some areas less than 200 meters, the NMC warned.
China's meteorological alerts are categorized as blue, yellow, orange and red as the severity ascends.
