BEIJING — China's national observatory on April 2 renewed a yellow alert for heavy fog in eastern and southern parts of the country.

During the daytime on April 2, thick fog is expected to sweep the coastal waters of Zhejiang and Fujian as well as parts of the East China Sea, according to the National Meteorological Center (NMC).

Visibility in some affected areas will be reduced to less than 1,000 meters, said the NMC.

It said drivers should slow down to safe speeds, and airports, freeways and ports should take appropriate safety measures.

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