Persistent fog has affected more than 200 ships since it descended on the mouth of the Yangtze River in Shanghai on Thursday, port authorities said.
The misty weather has reduced average visibility to less than 1,000 meters since midday Thursday and in some areas, visibility is below 200 meters, said officials at Waigaoqiao checkpoint.
Waigaoqiao is Shanghai's free trade zone and has one of the city's leading ocean shipping ports.
In the 26 hours from 8 a.m. Thursday to 10 a.m. Friday, 130 incoming vessels canceled or postponed their port calls to Shanghai, and about 80 outgoing ships were fog-bound at Shanghai port, the officials said.
The Shanghai meteorological station warned of the first heavy fog of this autumn on Tuesday. "The fog, plus Thursday's rain, has also stopped the ferry services and closed several inter-provincial expressways," said chief meteorologist Man Lipingon Friday.
She said the weather was expected to clear on Saturday, when wind would hopefully dispel the rain and fog, but the temperature would fall by an average 5 to 7 degrees Celsius to around 10 degrees.
Friday marks the "beginning of winter" in the Chinese lunar calendar and most parts of the country are expecting significant temperature drops.