According to the National Weather Service, the red alert is that temperatures are expected to reach 40 degrees Celsius (104 Fahrenheit) in the next 24 hours.
Authorities also issued warnings for regions from central Shaanxi province to Jiangsu province on the east coast. According to the Central Meteorological Observatory, temperatures may rise above 40 degrees Celsius in Zhejiang, Sichuan and Yunnan provinces on Wednesday.
Temperatures have been rising for several days, with Shanghai raising its red alert for the first time this year on Sunday as the financial center scorched 40 degrees Celsius, according to state tabloid The Global Times.
Shanghai has experienced just 15 days with temperatures above 40 degrees Celsius since records began in 1873, the Shanghai Meteorological Service said on Sunday.
Vendors in the city reported an increase in sales of ice cream, melons and crabs chilled in liquor, a popular summer dish. Eight metric tons of ice are used every day to cool lions, pandas and other animals at the sprawling Shanghai wildlife park.
According to The Global Times, other parts of the country, such as the southwestern Sichuan Basin, also experienced record high temperatures this year.
In Chongqing, which has issued a red alert, the roof of a museum melted, exploding traditional Chinese tiles as the heat melted the resin underneath. The city has activated trucks to spray water to cool the roads.
Elsewhere, residents try to cool off in different ways. On Sunday, large crowds flocked to the beach in Qingdao, eastern Shandong province, to swim in the sea. In Nanning, Guangxi, children played barefoot in public fountains. In Nanking, Jiangsu province, residents retreated to an air-raid shelter to escape the heat, reading newspapers and watching TV to pass the time in their Wi-Fi-equipped wartime bunkers.
In its statement, the Central Meteorological Observatory asked local officials to take measures to prevent heat and fires. Residents should avoid outdoor activities and take protective measures – especially the young, elderly and those with health problems.
China’s contrasting summer this year has brought disaster from both heat waves and heavy rains. Citing climate change, officials have warned against disasters since mid-July, which is usually the hottest and wettest time of the year.
China’s annual flood season traditionally begins in June and is usually worst in densely populated agricultural areas along the Yangtze River and its tributaries – but in recent years it has become more intense and dangerous, and experts warn that climate change could make the situation worse.
Additional reporting by Reuters.
