Guangdong raised its wind emergency response to the highest level at 10am on Tuesday as Typhoon Ragasa is forecast to make landfall along the central or western coastal areas of the province as a strong or super strong typhoon within 24 hours.

The move came as China’s National Meteorological Center forecast the typhoon would make landfall between Shenzhen and Xuwen county in Guangdong on Wednesday.

It also comes as China ordered a shutdown of schools and businesses in at least 10 cities ahead of Super Typhoon Ragasa slamming into the country's south.

"Except for emergency rescue personnel and those ensuring people's livelihood, please do not go out casually," the emergency management authorities in the city of Shenzhen said in a statement, adding that work and market closures will begin in the afternoon.

The technology hub's authorities said they have prepared more than 800 emergency shelters and ordered the evacuation of 400,000 people, with its emergency management authorities warning of "severe wind, rain, waves and floods".

Mainland authorities have activated flood-control measures in several southern provinces, warning of heavy rain from late on Tuesday.

Shenzhen airport will halt all flights from Tuesday night.

Macau has activated its emergency response mechanism as it expected Ragasa to pass within 100 kilometres to its south on Wednesday morning.

Residents in Macau are also bracing for significant impact, with school closures and evacuation plans under way.

Other cities in Guangdong that are implementing the suspension measures include Chaozhou, Zhuhai, Dongguan and Foshan.

Residents crowded into markets and grocery stores to stock up ahead of Ragasa's arrival.

Shelves of fresh meat and vegetables were mostly bare at a supermarket in Shenzhen's Bao'an district on Monday evening.

Checkout queues were long in the bustling store as people hurried around to pick up supplies.

A supermarket employee said bread had already sold out by midday. (Xinhua/Agencies)