China will shiver as Spring Festival begins, with a strong cold snap sweeping across the country on Wednesday, dumping heavy snow on most southern regions and challenging the millions who are traveling home.

The lowest temperature, in Hulunbuir, North China's Inner Mongolia autonomous region, was -44 C on Wednesday, freezing roads and triggering frozen fog that created chaos on roads.

Cold weather is expected to continue after the National Meteorological Center issued a blue alert on Wednesday, predicting heavy snow for Thursday and Friday in Hubei, Anhui, Jiangsu, Zhejiang, Jiangxi and Hunan provinces and the Shanghai municipality. Temperatures were expected to drop by 10 degrees.

Snowfall of up to 15 cm is expected within 30 hours, the center said.

The Chinese meteorological authority uses a four-tier color-coded weather warning system, with red being the most severe, followed by orange, yellow and blue.

Chen Zhenlin, a spokesman for the China Meteorological Administration, asked local authorities to fully prepare for snowstorms - cleaning the roads, checking railways and communication services, and guaranteeing the power supply.

While most southern parts of the country will be hit by snow and freezing rain, northern areas such as Liaoning, Jilin and Heilongjiang provinces and Inner Mongolia will see a temperature drop of up to 12 degrees on Thursday.

The temperature will fall further from Saturday to Feb 15, about 3 to 4 degrees below the average of the past two decades, the center said.

The cold snap brought widespread disruption to transportation services, slowing down many people's trips back home during the Wednesday-through-Friday Spring Festival travel peak.

The Ministry of Railways said more than 6.3 million people took train trips in the country on Thursday, the most since the travel rush began on Jan 26.

Tao Liping, spokesman for the Shanghai Railway Bureau, said more than 320,000 people left Shanghai by train on Thursday - the 13th day of the Spring Festival travel season.

Two-hundred and forty additional trains were put into operation on Thursday, the most since the travel season started.

Rain in Shanghai turned to sleet and snow on Thursday afternoon. The city's Meteorological Bureau said the snow was caused by the mixture of cold and warm air, and that most of the snowfall was expected from Thursday night to Friday.

More than 30,000 square meters of underground parking space at Shanghai Hong-qiao Railway Station and Shanghai Railway Station can be used as emergency waiting room for up to 40,000 passengers if trains are delayed because of the weather, officials said.

"The snow should accumulate with some ice on the road," said Zhu Jiehua, an officer of the Shanghai Meteorological Bureau.

However, highways connecting Shanghai to nearby provinces and cities are still open to those hurrying home.

"We won't close the highway unless the icy road situation gets worse," said Gao Junjie, an official with Shanghai's Songjiang district road administration, adding that temperatures were still above freezing in Shanghai on Thursday.

Gao said the highway didn't close during last few year's Spring Festival peak travel season.

Yang Hong, a 53-year-old homemaker, said she bought for her family three Friday-night train tickets from Shanghai to Nanjing to have their reunion dinner, even though her original plan was to drive home.

"You've got to play it by ear. If the snow is heavy and the way home is closed, I'll take the train, but if that's not the situation, we'll drive home and return the tickets," she said.

Driving is not a good choice for most southern parts of the country, with snow and freezing rain there since Wednesday evening.

On Wednesday, one person died in rear-end collisions involving more than 20 vehicles on a highway from Chengdu to Nanchong in Sichuan province. The collisions were blamed on heavy fog that followed the sudden temperature drop.

The freezing cold on Thursday pushed up prices of the country's fruits, vegetables and meat by about 2.6 percent over the day before, according to the Ministry of Agriculture.

Contact the writers at wangqian@chinadaily.com.cn and shiyingying@chinadaily.com.cn