Almost 500,000 people were evacuated as the powerful typhoon was previously forecast to hit the eastern coast near Shanghai over the weekend.
But Muifa changed course while at sea, packing winds of 178 kilometres (110 miles) an hour, the national meteorological centre said Sunday.
The temperamental storm, which has already changed speed and direction several times, is now due either to make landfall in the eastern province of Shandong Monday morning or to keep moving north along the coast, it added.
The two airports in Shanghai halted the majority of flights on Sunday, the Oriental Morning Post said, following the cancellation of more than 200 flights the previous day, which affected nearly 30,000 passengers.
The storm -- which had originally been forecast to be Shanghai's worst since 2005, when Typhoon Matsa killed seven people and caused 1.3 billion yuan ($202 million) in damage -- brought strong winds and rain to the metropolis Sunday.
At least one person went missing in the neighbouring province of Zhejiang when a boat sank, the official Xinhua news agency reported.
But there were no reports of major road blockages or downed trees in the commercial city.
The eastern provinces of Jiangsu and Shandong -- next in line -- were meanwhile bracing for the impact of the storm, evacuating tens of thousands of people and ordering more than 11,000 boats back to shore, media reports said.
Authorities have warned that the typhoon could affect an even wider area than initially predicted if it continues to hug the eastern coast and makes landfall further north.
"In this case, Muifa would affect the whole eastern and northern sea area," the government's National Marine Environmental Forecasting Centre has said.