China is facing a 40C (104F) heatwave, with some provinces already on the highest possible alert and officials are warning of glacial melt, mudslides and forest fires.
Following above-average temperatures in June and early July, Saturday is the day of 'big heat' in the Chinese lunar calendar.
The Ministry of Emergency Management has said that the surge in demand for air conditioning across homes, offices and factories could pose risks to the national power grid.
Leo Zhang, president of the chemical maker Sika China, said on Friday: "For all the factories in China and in Shanghai we have regulations that need to be followed", after government officials warned of "severe tests".
In rural regions, such as Xinjiang, on the border with Kyrgyzstan, drought could see crops ruined.
Xinjiang, home to China's Uyghur population, is also where 20% of the world's cotton is produced.
Elsewhere in the province, potential glacial melt could result in dam failure.
"Continued high temperature has accelerated glacial melting in mountainous areas and caused natural disasters such as flash floods, mudslides and landslides in many places", Chen Chunyan, chief expert at the Xinjiang Meteorological Observatory told state media.
20 provinces on high alert
Some 20 of China's 31 provinces have been told to brace for extreme temperatures, with coastal areas and Shanghai set to be the worst affected, according to the National Meteorological Centre. Experts mostly blame climate change.
The city of Chongqing and parts of Hunan, Guangdong, Zhejiang and Jiangxi are all also at risk of forest fires.
Maximum temperatures in China are largely unverified, with a local news outlet reporting 50.3C (122.5F) at a weather station near Ayding, Xinjiang in 2015.
In July, officials in Shanghai said temperatures of 40.9C (105.6F) equalled the highest on record, which was first achieved in 2017.
Temperatures in some regions could reach 50C (122F) by next week, the Meteorological Administration claimed on Friday.