People cool themselves by having dinner on the river bed in Pianyan town, Southwest China's Chongqing on Sunday. Photo: CFP

The China Meteorological Administration (CMA) Tuesday issued a level two emergency response for the first time, after a heat wave in eastern and southern China sent temperatures to record highs and claimed several lives.

The emergency response came after the National Meteorological Center (NMC) issued an orange alert for heat, the second-highest level possible, for four consecutive days in East China's Anhui, Jiangsu, Zhejiang, Jiangxi, Fujian provinces and Shanghai, Central China's Hunan and Hubei provinces as well as Southwest China's Chongqing.

It was the first time in history that the CMA had issued such a response.

Temperatures are expected to climb as high as 41 C in central Zhejiang, southeast of Sichuan Basin and parts of the Xinjiang Uyghur Autonomous Region, Xinhua quoted the CMA as saying.

The CMA forecast that temperatures over 35 C will linger along the Yangtze River and the Huaihe River, regions south of the Yangtze River and Chongqing from Tuesday to August 8.

According to statistics from the National Climate Center, which is affiliated with the CMA, since July 1 the heat wave has spread across one third of China's territory. And an area of 189,000 square kilometers, almost the size of Syria, saw temperatures soaring above 35 C for more than 20 days in July.

This year saw more hot days because subtropical high pressures are stronger and more stable than ever, Zhang Mingying, an expert with the Beijing Municipal Meteorological Bureau, told the Global Times, advising people to cut down on outdoor activities when temperatures are high.

In Shanghai, the mercury climbed to 40.6 C on July 26, the highest temperature recorded in the city. With temperature topping 39 C, Tuesday became the 24th high temperature day in July, making it the hottest July in 140 years.

The sizzling temperatures in the city led to the deaths of a 63-year-old woman and a 51-year-old man from heat stroke over the weekend. There was one death in Nanjing, the capital of Jiangsu Province, and two in Changsha, the capital of Hunan Province.

One of the deceased in Changsha was a 36-year-old migrant worker, who reportedly worked 38 days in a row during the heat wave.

Elsewhere, Fenghua, a city in Zhejiang, recorded a temperature of 42.7 C, becoming the hottest in the country. Hangzhou, capital of Zhejiang, also saw its high temperature surpassing 40 C for five consecutive days, setting a record for the city.

"There is more extreme weather as the world's climate is becoming warmer, but human activities also contribute to the increase in temperature." Zheng Yan, a research fellow with the Institute for Urban and Environmental Studies at the Chinese Academy of Social Sciences, told the Global Times.

Several provinces are suffering through a drought as the heat wave continues to scorch a wide swathe of land where flooding is usually the problem during the rainy season.

Drought has affected 12.2 million people in mountainous Guizhou Province, leaving 2 million people there to deal with temporary drinking water shortages and damaging 840,000 hectares of crops, the provincial government said on Tuesday.

Thirty-three counties and cities in Hunan are also facing severe drought, as the province received less than 30 percent of expected rain this month.

Public attention has fixed on the late migrant worker in Changsha and the labor issues involved. To help workers to get some relief from the heat, companies should pay their employees a heat subsidy, according to the regulations. In Shanghai, workers theoretically receive an allowance of at least 200 yuan ($32.6) per month from June to September when temperatures are high. The size of the allowance varies in different places.

However, about one third of the workers in Shanghai do not receive the allowance, Tang Fuqiang, a Shanghai-based lawyer with the Beijing Yingke Law Firm, told the Global Times.