Almost a third of flights from Shanghai's two international airports have been cancelled, the city's news service said, totalling around 640.

The Shanghai Central Meteorological Observatory on Wednesday afternoon upgraded an earlier yellow rainstorm alert to orange, the second-highest warning level.

Typhoon Co-May made landfall in eastern Zhejiang Province at about 4:30 am Wednesday (2030 GMT Tuesday), with winds near its centre of 83 kilometres per hour.

It is expected to make a second landfall in financial hub Shanghai in the evening.

"From last night to 10:00 am today, 282,800 people have been evacuated and relocated, basically achieving the goal of evacuating all those who needed to be evacuated," state broadcaster CCTV reported.

More than 1,900 temporary shelters have been set up across the city, authorities said.

Sheets of rain inundated the city without pause on Wednesday, with pedestrians bracing their umbrellas against gusts and delivery drivers splashing through huge puddles as they made their way through sodden streets.

Ferry services have been cancelled, additional speed limits are in place on highways, and there has been some disruption to metro and train services in the city.

However, Shanghai's Legoland and Disneyland remained open on Wednesday morning.

- Wave warning -

As the typhoon tracked northwest after making landfall in the morning, live shots from China's east coast showed waves overrunning seaside walkways, while broadcasts from the city of Ningbo showed residents sploshing through ankle-deep water.

Separately, China issued a tsunami warning for parts of the eastern seaboard after a magnitude-8.8 earthquake struck off Russia's Kamchatka Peninsula.

However, the warning was later lifted, according to CCTV.

Co-May was downgraded to a tropical storm before leaving the Philippines, and then strengthened again over the South China Sea.

Its passage has had an indirect link to extreme weather in China's north at the moment, Chen Tao, chief forecaster at the National Meteorological Center, told the state-run China Daily.

Heavy rain there has killed more than 30 people and forced authorities to evacuate tens of thousands, state media reported Tuesday.

"Typhoon activity can influence atmospheric circulation... thereby altering the northward transport of moisture," Chen said.

Natural disasters are common across China, particularly in the summer when some regions experience heavy rain while others bake in searing heat.

China is the world's biggest emitter of the greenhouse gases that drive climate change and contribute to making extreme weather more frequent and intense.

But it is also a global renewable energy powerhouse that aims to make its massive economy carbon-neutral by 2060.