More than five million people in southwest China faced power cuts with a heatwave-induced electricity supply crunch, forcing factories to close.

Demand for air conditioning grew substantially as temperatures across Sichuan province surpassed 40 degrees Celsius (104 Fahrenheit) in recent days. To exacerbate the condition further, the region, which relies heavily on dams to generate its electricity, saw its reservoirs dry up due to the heat.

A local power company said Dazhou, a city of 5.4 million people in the northeast of the province, would receive only intermittent supply, according to a Shanghai-based online media outlet. Residents underwent outages up to three hours or longer.

Factories in Sichuan, including a joint venture with Japanese automaker Toyota, have been forced to halt work after government officials said they would prioritize power to residential areas over commercial operations.

The world's largest maker of batteries for electric vehicles, Contemporary Amperex Technology, has similarly halted production in Yibin city, according to Chinese media.

Sichuan produces half of the nation's lithium, used in batteries for electric vehicles, and its hydropower projects provide electricity to major industrial hubs along China's east coast. But 19 out of 21 cities in the province have been ordered to suspend industrial production until Saturday, according to a notice issued over the weekend.

Multiple major cities in China have recorded their hottest days ever this year, and the national observatory renewed a red alert for high temperatures – the most serious warning in its four-tier system.

Water volume in Sichuan's major rivers has fallen 20 to 50% in the absence of rain, severely affecting hydropower generation, state news agency Xinhua reported, citing provincial energy officials.

The China Meteorological Administration said the country was going through its longest period of sustained high temperatures since records began in 1961, with 64 days straight of heat warnings in various regions starting in June.

More than a third of weather stations in China recorded extreme heat this summer, with 262 of them reaching or surpassing previous records, the administration said.

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