"Pollutant discharge and unfavourable weather" will cause the smog, expected to last until Wednesday, the Ministry of Environmental Protection predicted in a circular.
The dominant pollutant will be PM2.5, particles with a diametre smaller than 2.5 micrometres, said the ministry.
It has issued an emergency notice to local governments in the region, urging them to be alert to smog and provide warnings to the public.
The notorious air pollution suffered by Beijing and its surrounding areas is caused in large part by vehicle exhaust emissions and coal burning in heavy industries and municipal heating in winter.
