China is enduring a summer of extremes, with heat waves scorching wide swaths of the country while rainstorms pummel other regions.

Climate change -- which scientists say is exacerbated by greenhouse gas emissions -- is making such weather more frequent and more intense.

Around 80,900 people had been evacuated by Tuesday afternoon in the southwestern province of Guizhou, state news agency Xinhua reported.

"It's very bad this time," Xiong Xin, a member of a rescue team who was in Rongjiang county on Tuesday, told AFP, describing the flooding as a "once-in-50-year event".

Images shared with AFP by Xiong showed a row of shops on the first floor of a building submerged, with residents leaning out of second-floor windows.

In Rongjiang a football field was "submerged under three metres of water", Xinhua said.

Rescuers pushed boats carrying residents through murky, knee-high water and children waited in a kindergarten as emergency personnel approached them, the footage showed.

One resident in an affected area told Xinhua "the water rose very quickly".

"I stayed on the third floor waiting for rescue. By the afternoon I had been transferred to safety."

Footage from state broadcaster CCTV showed severe flooding has inundated villages and collapsed a bridge in one mountainous area of the province.

A team was also seen preparing a drone to deliver supplies including rice to flood victims.

In a video circulated by local media, truck driver You Guochun recounted his harrowing rescue after he ended up perched over the edge of a broken bridge segment.

"A bridge collapsed entirely in front of me," he said.

"I was terrified."

- Alerts -

China's top economic planning body has allocated 100 million yuan ($13.95 million) for disaster relief in Guizhou, Xinhua said.

Floods have also hit neighbouring Guangxi region, with state media publishing videos of rescuers there carrying residents to safety.

Tens of thousands of people were evacuated last week in the central province of Hunan due to heavy rain.

And nearly 70,000 people in southern China were relocated days earlier after heavy flooding caused by Typhoon Wutip.

Chinese authorities issued the year's first red alerts last week for mountain torrents in six regions -- the most severe warning level in the country's four-tier system.

Some areas in the affected regions were "extremely likely to be hit", Xinhua reported, with local governments urged to issue timely warnings to residents.

Authorities in Beijing this week issued the second-highest heat warning for the capital on one of its hottest days of the year so far.

Last year was China's hottest on record.

China is the world's largest greenhouse gas emitter but is also a renewable energy powerhouse, seeking to cut carbon dioxide emissions to net zero by 2060.