More than half a million homes lost power across Taiwan Wednesday and five people were injured as Super Typhoon Meranti hit the island, but the typhoon labelled "the world's strongest so far this year" lost much of its strength as it slammed into southeastern China on Thursday.

Taiwan's Central Weather Bureau warned that the Category 5 storm threatened several southern and eastern cities, including Kaohsiung and Hualien, with strong winds, torrential rain and flooding.

Meranti, which grew in strength the closer it got to Taiwan, was carrying maximum winds of 227 km/h as it clipped the south of the island, the weather bureau said.

"This typhoon is the world's strongest so far this year," weather bureau spokeswoman Hsieh Pei-yun said.

Taiwan's Central Emergency Operation Centre said five people were injured, while many power lines were brought down, some by falling trees, cutting electricity to 550,000 households.

"The damage from Meranti will continue to rise as the storm slams the island," said emergency centre spokesman Li Wei-sen.

"Losses probably cannot be avoided, but we'll try to minimize casualties."

Trains and shipping services were disrupted, while offices and schools in Kaohsiung and other cities were closed and almost 1,500 people were evacuated from their homes, the centre said.

A local resident removes a rock from a blocked road in southern Pingtung county. The Category 5 storm Meranti brought winds up to 216 km/h on Wednesday. (Sam Yeh/AFP/Getty Images)

Most domestic flights have been cancelled, including all of those from Kaohsiung airport, where international flights were also severely affected.

Meranti barrels into China

Taiwan felt the full force of Meranti Wednesday and into Thursday before it barrelled into China.

Although the official China News Service said the storm could be the strongest typhoon to hit southeastern China since 1969, Meranti lost much of its strength and will continue to lose strength as it pushes inland and up toward China's commercial capital of Shanghai. However, it will bring heavy rain.

Cars drive past collapsed power lines, partially blocking the road, as Super Typhoon Meranti skirts Pingtung county, in southern Taiwan, on Sept. 14, 2016. (Sam Yeh/AFP/Getty Images)

Typhoons are common at this time of year, picking up strength as they cross the warm waters of the Pacific and bringing fierce winds and rain when they hit land.

Meranti comes just over two months after the deadly typhoon Nepartak cut power, grounded flights and forced thousands to flee their homes across central and southern areas of Taiwan.

In 2009, Typhoon Morakot cut a swath of destruction through southern Taiwan, killing about 700 people and causing up to $3 billion in damage.