Thick fog will shroud China's northern and central regions Sunday morning, the National Meteorological Center said, warning of increasing safety risks on road and at airports.

The country's top meteorological authority issued a yellow alert at 6 a.m., suggesting people in fog-affected areas to cancel outdoor activities as the fog will worsen the regions' air quality.

Fog and haze will decrease visibility to within 1,000 meters in some parts of the provinces of Hebei, Shandong, Henan, Hubei, Sichuan, Liaoning and Zhejiang, with visibility of less than 200 meters in some areas, the center said.

The center said that a cold front will sweep north China over the next three days, bringing winds and a temperature drop of 4 to 6 degrees Celsius to Xinjiang Uygur Autonomous Region, Inner Mongolia Autonomous Region and northeast China.

Some of these regions may see rainfall or snow over the next three days, the center said.