People visit the Nanyue Hengshan Scenic Area after a snowfall in Hengyang, China, on Sunday. AFP

In a week of unexpectedly frigid weather, temperatures have fallen to lows below zero in northern areas, disrupting road, rail and air transport and even causing a brake failure in a commuter train in Beijing, the capital.

Forecasters early in November had predicted a warmer winter this year due to the El Nino phenomenon, while warning that temperatures could fluctuate after one of the warmest Octobers in decades.

On Monday in Guangdong, where snow is generally limited to the northernmost areas, snowfall blanketed the top of a mountain in a city just 80km north of the provincial capital Guangzhou by the coast.

A low of 8˚C  was forecast for Guangzhou, compared to the province's typical early winter temperatures that hover in the double digits, while January averages around 14˚C.

Guangzhou officials urged precautions, especially for the old and young who may be vulnerable to "cold wave illnesses," as winter advances.

In neighbouring Guangxi, where President Xi Jinping called last week for an "all-out" emergency response, sleet has been forecast for some cities, including Guilin. Snow flurries were seen in the commercial hub of Shanghai on Monday.

In Beijing, Monday morning temperatures dropped to minus 15.5˚C — near the 1952 historic low of minus 15.2˚C for Dec.19 and minus -17.7˚C for Dec.20 that year. The lowest recorded December temperature was minus 18.3˚C.

TRAPPED TOURISTS

Low temperatures will prevail until Thursday, the national forecaster warned, with northern areas, Inner Mongolia and some areas around the Yangtze river to be 7˚C lower than is typical.

On Monday, the city of Hohhot in Inner Mongolia, is expected to experience a low of minus 22˚C while the mercury will sink to minus -5˚C in Zhengzhou, in the central province of Henan.

Rain and snow could lash the middle and lower reaches of the Yangtze and its south, including parts of Anhui, Jiangsu and Zhejiang provinces as well as Shanghai. Local heavy snow can be expected, the forecaster added.

Taking advantage of the early sub-freezing weather, Harbin, a city in the northeastern province of Heilongjiang, will host its largest-ever ice sculpture festival in a park sprawling across 810,000 sq-m.

More than 1,000 ice and snow features landscapes in the park have been fashioned from about 250,000 cubic metres of ice and snow harvested from the frozen Songhua river. But efforts to cash in on the cold weather led to a downside for more than 50 tourists trapped for over two hours on Saturday in cable cars ascending a mountain in eastern Zhejiang province, after windy weather triggered a halt for safety reasons. All were unharmed despite freezing conditions in the cable cars, media said.

Reuters