Typhoon Chanthu sent debris flying through the air in southern China's Guangdong province on Thursday, bringing rain that could aggravate the country's worst floods in a decade.

No casualties have been reported so far from Chanthu, which was upgraded from a tropical storm one day earlier. Authorities urged residents to stay indoors as winds reached up to 115 kilometres per hour.

The storm comes as China grapples with severe flooding that has left more than 701 people dead and 347 missing so far this year, according to the flood prevention agency. The death toll is the highest since 1998, when more than 4,000 people died. Damages are in the tens of billions of dollars.

In Guangdong, floods have killed more than a dozen people and forced the evacuation of tens of thousands, the state-run Xinhua news agency has said. Landslides triggered by heavy rains crushed homes and floods have wiped out crops across the province since June.

Chanthu reached Leizhou city in Guangdong early Thursday and was rumbling north along the coast of Guangdong's southern tip, China's Meteorological Administration said. The storm was expected to travel farther inland toward the Guangxi region later in the day, the administration said.

State broadcaster CCTV's noon broadcast showed intense winds tossing around large pieces of debris and objects such as pipes and shingles in Maoming prefecture. Two people were killed in southern China last week by falling debris from Typhoon Conson.

Calls to the Guangdong provincial government office rang unanswered on Thursday.

More torrential rains are expected across China this week, in provinces ranging from Yunnan in the southwest to Jilin in the northeast.