Heatwaves to menace China as almanac's 'big heat' day looms

China will suffer the return of more heatwaves over the next 10 days from east to west, with some coastal cities already on their highest alert level and inland regions warning of dam failure risks because of melting glaciers.

A sharp temperature spike is expected tomorrow, before building up into heatwaves, defined as periods of atypically hot weather of three days or more.

Tomorrow is the day of the "big heat" in the Chinese Almanac based on the lunar calendar.

The hot spell is expected to be similar in scope to heatwaves from July 5-17, but more regions could be hit by temperatures of 40 degrees Celsius or higher, said Fu Jiaolan, chief forecaster at the National Meteorological Centre, to state media.

Some cities in Zhejiang province, home to many factories and exporters, issued red alerts today, the highest in a three-tier warning system, forecasting temperatures of at least 40C in the next 24 hours.

The load on the national power grid could reach a new high this summer as demand for air-conditioning by homes, offices, and factories surges, with safe operation facing "severe tests", warned the Ministry of Emergency Management today.

"For all of the factories in China and in Shanghai we have regulations that need to be followed," said Leo Zhang, president of chemical product maker Sika China.

"Every year we do things to make the work more comfortable, for example giving workers ice-creams when it gets too hot."

Zhejiang, as well as parts of Fujian, Guangdong, Hunan, Jiangxi, and the city of Chongqing, also stand at risk of forest fires in the near term, the ministry said.

Glacial melt

In the western region of Xinjiang, accelerated glacial melt through July 29 poses risks to rivers and dams, said the China Meteorological Administration today.

It particularly warned of a high risk of dam failure on a tributary of the Aksu River near China's border with Kyrgyzstan.

This round of hot weather will have "a certain degree of impact" on the melting of alpine snow and ice, the administration said.

The heat in China this summer has been described as extreme.

From June 1 to July 20, the Yellow River and Yangtze River basins - major centres of industry and commerce - were hit by at least 10 high-temperature days more than the norm.

Heatwaves have also scorched other parts of East Asia, Western Europe, North Africa, and North America, sparking wildfires in many countries.

Scientists caution that climate change will only make heatwaves hotter and more frequent.

The highest-ever recorded temperature in China is a matter of debate.

According to Chinese media, the hottest period in the last 300 years was in July 1743 during the Qing dynasty, with a French missionary in Beijing said to have recorded an all-time high of 44.4C.

In 2015, a local news portal reported 50.3C at a weather station near Ayding, a dry lake in Xinjiang's Turpan Depression.

Temperatures in the oasis city of Turpan could reach 50C next week, said the China Meteorological Administration today.

- Reuters