Beijing issued a blue alert for smog on Thursday, the lowest level on its color-coded emergency system, although forecasts suggest the only thing that will be blue on New Year's Day is the sky.

In the southern part of the capital, air pollution is expected to worsen to the second-highest level (severe pollution) on Friday, while smog will blanket neighboring Tianjin and several cities in Hebei province, according to data from the local governments.

Tianjin has issued a yellow alert, while Shijiazhuang, the Hebei capital, issued the highest warning－a red alert－on Thursday.

During a red alert, factories are ordered to suspend production to reduce emissions, and trucks delivering industrial raw materials are banned from roads within the city.

"Strong wind from the north should disperse the air pollution after Friday, bringing back blue skies across northern China," said Li Mingmei, deputy director of public services for the China Meteorological Administration.

A cold front will sweep the vast northern and eastern regions to send temperatures dropping by up to 8 C, with snow expected in the northeast and rain in the south, she said.

For a large part of the country, the New Year holiday, which runs Saturday to Monday, will see clear sunshine, Li added.

However, according to the administration, the Xinjiang Uygur autonomous region has been experiencing a cold front since Wednesday, resulting in this winter's strongest blizzard hitting the regional capital of Urumqi and other cities.

Residents encountered snow up to 1 meter deep on roads on Thursday, affecting traffic on expressways, and some schools were forced to suspend classes.