BEIJING, Feb. 16 (Xinhua) -- China's national observatory issued a yellow alert for heavy fog in central, eastern and southern areas Friday.

The fog will hit parts of Anhui, Fujian, Guangdong, Guangxi, Hainan, Henan, Hubei, Hunan, Jiangsu and Jiangxi from Friday evening to Saturday morning, according to the National Meteorological Center (NMC).

In some areas of Anhui, Fujian and Jiangxi, visibility may fall below 200 meters.

A cold front is expected in northern China from Friday evening to Monday, bringing low temperatures. Some areas in northwestern and northern China will see temperatures drop by over ten degrees Celsius, said the NMC.

China has a four-tier color-coded warning system for severe weather, with red being the most serious, followed by orange, yellow and blue.