Shanghai and several provinces have dealt with the heat wave for much of this month.
Temperatures in Shanghai topped 102 degrees F Tuesday, the eighth consecutive day readings climbed above 100, the Shanghai Meteorological Center said.
The Shanghai Municipal Center for Disease Control and Prevention said the high temperatures caused a spike in the number of sunstroke patients in the city, Xinhua reported.
With 24 days of temperatures of at least 95 so far, July has been the hottest for Shanghai since weather records began 140 years ago, Xinhua said.
The local health agency said more than 30 percent of the patients who died were overcome by the summer heat while indoors.
The relentless heat prompted the China Meteorological Administration to issue a Level 2 emergency response, the second most serious weather alert in the four-tier ranking system, Xinhua said.
The emergency response included the provinces of Anhui, Jiangsu, Zhejiang, Jiangxi, Hunan, Hubei, Fujian, along with the cities of Shanghai and Chongqing.