BEIJING (AFP) - A crippling drought exacerbated by a record heat wave has spread out across half of China and reached the normally frigid Tibetan Plateau, according to official data released ahead of more searing temperatures on Thursday (Aug 25).

The world's second-largest economy has been hit by record heat, flash floods and droughts - phenomena that scientists say are becoming more frequent and intense due to climate change.

Southern China has recorded its longest continuous period of high temperatures since records began more than 60 years ago, the Agriculture Ministry said this week.

Experts have said the intensity, scope and duration of the heatwave could make it one of the worst recorded in global history.

A chart from the National Climate Centre showed on Wednesday (Aug 24) that swathes of southern China, including the Tibetan Plateau, were experiencing "severe" to "extraordinary" drought conditions.

The worst-affected area - the Yangtze river basin, stretching from coastal Shanghai to Sichuan province in China's south-west - is home to over 370 million people and contains several manufacturing hubs, including the megacity of Chongqing.

The China Meteorological Administration predicted continued high temperatures of up to 40 deg C in Chongqing and in the provinces of Sichuan, Jiangxi and Zhejiang on Thursday.

But some regions gained relief from the heatwave. Parts of south-western Sichuan were battered by heavy rains overnight, causing the evacuation of almost 30,000 people, state broadcaster CCTV reported.

And in the south-east, Typhoon Ma-on made landfall in coastal Guangdong province and Hong Kong on Thursday morning.

“High temperatures have basically been alleviated in the regions of south China, Jiangxi and Anhui,” the meteorological administration said.

“But high temperatures will continue for the next three days in regions, including the Sichuan basin and provinces surrounding Shanghai.”

'Severe threat'

China's State Council on Wednesday announced a 10 billion yuan (S$2.03 billion) subsidy to support rice farmers experiencing drought conditions that the authorities have warned pose a "severe threat" to this year's autumn harvest.

China produces more than 95 per cent of the rice, wheat and maize it consumes. But a reduced harvest could mean increased demand for imports in the world's most populous country, putting further pressure on global supplies already strained by the conflict in Ukraine.

Officials also called for "a combination of measures to increase water sources to fight drought, first ensure drinking water for the people, ensure water for agricultural irrigation", the readout added.

Wednesday's CCTV evening news broadcast showed trucks supplying villagers who lacked drinking and agricultural water in rural Sichuan and Chongqing, with remote mountain areas particularly hard hit.

Chongqing and Sichuan have also been battling wildfires since last week, exacerbated by high temperatures and water scarcity.

Temperatures as high as 45 deg C have led multiple Chinese provinces to impose industrial power cuts, as cities struggle to cope with a surge in demand for electricity partly driven by people cranking up the air conditioning.

Record low water levels on the Yangtze River have also put pressure on the region's hydropower generators.

The heat broke records in Sichuan, where a temperature of 44 deg C was recorded Wednesday afternoon, the province's Meteorological Service Centre said in a statement.