A woman waits for a taxi in the snow on a road in Hunchun, Northeast China's Jilin province, Jan 19, 2016. [Photo/Xinhua]

The strongest cold wave in decades is about to sweep across China as people were advised to stay indoors and warned of upcoming heavy snow and freezing rain in the next few days.

According to the weather forecast, Beijing this Friday will face a low that may drop below -16.7 degrees Celsius. It's a record low temperature first recorded in this century on Jan 6, 2010.

Shanghai will feel the coldest air in three decades in upcoming days, with its suburban area expected to endure a temperature of -8 degrees - and even -10 degrees on Sunday and Monday, according to the Shanghai Meteorological Service.

The Ministry of Transport announced Wednesday a highway traffic emergency, its highest warning, urging transport agencies across the country to ensure a reliable transport infrastructure and safe transport of goods and passengers by spreading real-time weather and traffic information and arranging a 24-hour shift to monitor possible risks.

In Hangzhou, east China's Zhejiang province, heavy sleet forced the cancellation of many flights to cities in the Pearl River Delta in south China's Guangdong province on Wednesday.

The rare freezing weather is more of a "natural disaster" than a simple cold wave, said Guokr.com, a popular and influential science website, in a post on its Twitter-like Weibo account.

A polar vortex featuring very cold temperatures went south and settled in Siberia and will cause a lasting cold spell in major parts of China in the next few days, the website explained.

Besides the polar vortex, a northward subtropical high will produce strong rainfall, and even heavy snowfall, in eastern and southern parts of China, especially Zhejiang province, which is located where the polar vortex is expected to collide with the subtropical high.

This kind of cold wave is so strong that it was last seen in 1991, the website said, urging people to stay at home during the severe cold wave, if possible.

The website's post was reposted over 40,000 times and commented on 9,000 times in less than a day, showing how concerned people are about the cold wave.

"Wish my boss would let me have a few days off," one Weibo user said.

"Wondering if it is lucky or unlucky to see such a rare cold wave that's way older than me," another joked.

Extreme and rare as it is, experts say the bitter cold is unlikely to bring that much damage and disorder to people's lives, as did the last cold wave in the winter of 2008.

"Unlike the cold wave in 2008, consisting of several continuous days of sleet and freezing weather, the upcoming cold wave will not last long. Besides, it's in late January when the temperature is cold enough, so the temperature can't drop more," Zhang said.