BEIJING, Oct. 19 -- The heavy smog that has shrouded some regions of north China since Saturday will ease on Monday thanks to a cold front, according to a forecast by the national observatory on Sunday.

The National Meteorological Center (NMC) extended a yellow alert on Sunday for severe smog and air pollution in the region. Beijing, Tianjin, Hebei and Shandong will see haze until Sunday night, it said.

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

However, the smog will be short-lived as a cold front is expected later on Sunday to help disperse the smog.

The cold front will sweep across China, bringing temperature drops in Inner Mongolia and northeast China, the center said.

Meanwhile, medium to heavy rainfalls will hit the provinces of Sichuan, Chongqing and areas along the Yellow and Huaihe rivers, according to the NMC.