Strong winds and heavy rain whipped South China's Hainan province and parts of Guangdong province on Sunday, as Typhoon Kajiki passed over open waters to the south of Hainan and headed toward Vietnam's central coast.

A short video posted online by Guangdong Radio and Television showed winds snapping off tree branches, and heavily rocking a docked boat and sending waves sliding over the pier.

Kajiki gained strength as it moved westward over the sea with maximum sustained winds of 162 kilometers per hour, China's National Meteorological Center said.

Rainfall of 25 to 40 centimeters was forecast for southern parts of Hainan Island, including Sanya, a popular beach resort.

Hainan took extensive measures to prepare for Typhoon Kajiki, amid fears that it could be the strongest typhoon to hit the region in the past 40 years.

As Typhoon Kajiki approached, the province raised its emergency response to the highest level. The typhoon, the 13th of the year, intensified from a severe tropical storm to a full typhoon at 2 am on Sunday. It gained strength and headed toward Hainan's southern coast, with landfall or a close pass expected on Sunday evening, said Cai Qinbo, spokesperson for the Hainan provincial meteorological bureau.

Authorities in Sanya evacuated 31,843 people from potentially vulnerable areas to safety by 3 pm on Sunday, according to the city's publicity department. Temporary shelters were set up at some local facilities like primary schools to receive the affected.

Across the province, over 770,000 emergency supplies had been prepared for vulnerable areas. More than 2,800 rescue workers are on standby with necessary vehicles and equipment, said Wu Zhanchao, deputy head of the Department of Emergency Management of Hainan Province.

All 30,769 local fishing boats had either returned to port or were safely sheltered, with over 21,000 crew members moved to shore.

Residents were advised to avoid unnecessary travel, stay away from low-lying areas, temporary structures and the coast, and be alert for potential geological hazards.

In Sanya, measures included closing schools, offices, business operations, suspending public transportation and shipping, and shutting scenic areas.

Hotels in Sanya took comprehensive steps to ensure guest safety. Atlantis Sanya provided multilingual notices in Chinese, English and Russian in each guest room, detailing the latest weather updates, temporarily suspended facilities, and offered alternative indoor activities within the resort.

"I'm not worried about the typhoon at all because the tour guide and travel agency have a lot of experience in dealing with it. They explained the precautions during the typhoon and reminded us to stay indoors as much as possible," said Yelena Rostova, a Russian tourist visiting Sanya as part of a tour group.

"I hope the typhoon passes quickly so that my family and I can enjoy the sunny beaches and our vacation," she added.

With strong winds and heavy rain lashing the city, Wang Wen, a resident of Sanya, chose to stay home over the weekend. "It has not significantly affected my daily life," she said.

Agencies contributed to this story.