Shanghai residents walk on streets with umbrellas as the city's temperature hits 40 C again on August 11, 2022. Photo: IC

High temperatures of up to 40 C hit 15 Chinese provinces and municipalities as forecast by China's top meteorological authority on Thursday. Experts predict that the heat wave will linger as the climatic background that caused this widespread heat wave persists.

The National Meteorological Center (NMC) of the China Meteorological Administration (CMA) issued an orange high-temperature alert on Thursday morning, forecasting temperatures to surge to 35 C to 39 C in 15 regions including the southern basin area in Northwest China's Xinjiang Uygur Autonomous Region, the western part of North China's Inner Mongolia Autonomous Region, the middle and eastern parts of Southwest China's Sichuan Province, Central China's Hunan Province and East China's Zhejiang and Fujian provinces. 

Among these areas, including the eastern and southern parts of Northwest China's Shaanxi Province, the western and southern parts of Central China's Hubei Province, the southern part of East China's Jiangsu Province and the middle part of East China's Anhui and Southwest China's Chongqing Municipality, will suffer from heat waves of 40 C or above. 

From July 16 to 31, the nationwide average temperatures between July 16 and 31 reached 22.9 C, or 0.5 C higher than usual, and the fifth highest since 1961. 

The NMC expected that high temperatures will linger, including areas along the Yangtze River and Huaihe River, areas in South China and Sichuan Basin, with less rainfall than usual. 

The abnormal persistence of an extensive subtropical anticyclone is the most direct cause of the recent extreme high temperatures across China, Zheng Fei, a research fellow at the Institute of Atmospheric Physics of the Chinese Academy of Sciences, told the Global Times on Thursday. 

Under the control of the anticyclone system, sinking airflows prevail over most of the area and cause a significant rise in the near-surface temperatures, Zheng said, adding that the sinking airflows lead to clear weather with less cloud cover, which increases solar radiation and causes higher temperatures on the ground. 

Shanghai, in particular, has had record-breaking temperatures this year. 
At 11:40 am on Thursday, the Shanghai Central Meteorological Station elevated its orange warning for high temperatures to a red warning, the highest level of extreme weather warnings in China. 

Under the influence of a subtropical high, high temperatures in Shanghai's city center and some suburbs would exceed 40 C to 41 C, the station said. 

About 12:15 pm on Thursday, Shanghai's city center Xujiahui area recorded a reading of 40.1 C, the sixth high temperature day with a temperature of 40 C or above for this year, setting a new record for the number of extremely hot days in the city. 

It has been forecast that high temperatures of up to 40 C or 41 C may still occur in Shanghai in the next 10 days. 

Shanghai has recorded 20 extremely hot days with temperatures of 40 C or above since meteorological records began in the city in 1873. There were six days so far this year, the highest, five days in 2013, three days in 2017, two days each in 1934 and 2016, and one day each in 2009 and 2010. 

As of Thursday, Shanghai had recorded 38 high temperature days so far this year with the temperatures hitting 35 C or above, including 22 days with temperatures reaching 37 C or above and six days with temperatures reaching 40 C or above. 

Zheng believed that high temperatures across China will continue for a while, as the climatic background that caused this widespread subtropical high anomaly persists. 

That is to say, the position of the Pacific subtropical high tends to be a little more north and west than usual years and tends to persist for longer, which was caused by the La Nina event for the consecutive third year.