People stand on the Bund as buildings along the Huangpu river are seen shrouded in fog, amid a red alert for heavy fog in Shanghai, China December 29, 2023. The severe weather was due to high humidity and poor atmospheric diffusion conditions, the forecaster said. Image Credit: Reuters

Beijing: Year-end holidaymakers across China were bracing for possible transport disruptions after the weather bureau on Friday warned that heavy fog and haze would shroud areas from Hebei province in the north to southern Shanghai for the next 24 hours.

The Central Meteorological Observatory issued its first red alert for fog since 2017. Conditions were expected to improve from Saturday evening, when a cold wave of air is expected to blow over the country.

Severe foggy conditions were expected in parts of northern province Hebei, central province Henan, eastern provinces Anhui, Jiangsu, Zhejiang and Shandong as well as in the municipalities Shanghai and Chongqing from Friday morning, the National Meteorological Centre said.

Dense fog in predicted in parts of Hebei, Shandong, Anhui, Jiangsu and Shanghai leading to low visibility of less than 200 metres, and less than 50 metres in some areas.

In the north and areas between the Yellow River and Huai River, light to moderate haze is forecast, with heavy haze affecting Tianjin, Hebei, Shandong and Henan.

The severe weather was due to high humidity and poor atmospheric diffusion conditions, the forecaster said.

China has experienced a year of climate extremes.

Last week, most of the country was hit by a cold snap that rewrote records with sub-freezing temperatures, in contrast to the summer, when scorching heat that breached 52 degree Celsius (125.6 Fahrenheit) in the northwest blistered the country.

Summer storms also brought record rainfall to Beijing and flooding elsewhere.

On Friday, the central observatory told the public to tune into weather and traffic alerts, and advised them to reduce time outdoors. Residents in parts of Shandong, Anhui and in Jiangsu should avoid going out unless necessary, it added.

"You can't see clearly the road conditions and traffic lights ahead," the observatory said on social media.

In Shanghai, some ferry routes were temporarily suspended and some sections of highways, as well as a bridge to a container port, were temporarily closed. At the city's Bund waterfront, a thick grey fog all but obscured the colourful skyscrapers across from it.

In Jiangsu, some sections of several expressways remained shut since Thursday evening, while Hebei and Henan temporarily closed segments of multiple highways on Friday morning, citing weather conditions, according to state television CCTV and provincial capital authorities said.