China has evacuated hundreds of thousands of people and ordered at least 10 cities to close schools and some businesses as the strongest storm of the year bears down on its southern coast.

Hong Kong has upgraded its typhoon warning to eight - just two levels below the maximum - ahead of the arrival of Super Typhoon Ragasa.

The storm is expected to make landfall in China's Guangdong province on Wednesday, where some 370,000 people have been evacuated so far, as authorities warn of a catastrophic situation.

Ragasa has been dubbed the King of Storms by China's meteorological agency and is expected to move towards northern Vietnam in the coming days, potentially affecting millions.

On Tuesday, supermarket shelves in Hong Kong were wiped empty of fresh bread, vegetables, meat, and instant noodles as residents prepared to hunker down.

Hong Kong International Airport said it expected significant disruption to flight operations from 18:00 local time (10:00 GMT) on Tuesday until the next day.

More than 500 Cathay Pacific flights are expected to be cancelled, while Hong Kong Airlines said it would stop all departures from the city.

In cities across southern China, shop owners piled sandbags in front of their stores in preparation for the storm's arrival, with residents in low-lying areas next to the sea front particularly worried about tidal surges.

Some residents have taped up the windows of their homes and businesses, hoping to prevent their destruction.

Super typhoon Ragasa - equivalent to a Category 5 hurricane - packed wind gusts of up to 285 km/h (177 mph) at its highest point on Monday, triggering warnings of floods, storm surges, and landslides across the region this week.

It's not yet clear exactly how much climate change has affected Ragasa specifically. However, a warming world is expected to make tropical storms like typhoons and hurricanes more intense, according to UN scientists.

While Taiwan remained largely unscathed after Ragasa passed through, at least six people were injured and over 100 international flights cancelled. Ragasa also lashed through a remote island in the Philippines, killing at least one person and prompting additional evacuations.