The National Meteorological Center announced that the heat wave currently on orange alert will continue to be raised for the next 10 days. Authorities in Shanghai and Hubei Provinces also issued alerts.
The heat is expected to exceed 40 degrees Celsius. Shanghai municipalities of Anhui, Hubei, Jiangsu and Fujian are expected to have temperatures above 37 degrees Celsius in the next few days.
The Xujiahui area in Shanghai already hit 40.3 degrees this week. This is the third highest in the city's history.
Ma Xuekuan, the meteorological center's chief forecaster, said, "The recent heat, caused by a subtropical high, is noted for its wide scope, high intensity and long duration."
Around 700 million people are affected by the heat wave. According to the center's heat map, the heat wave is spread throughout the country.
The Hefei Commission of Urban-Rural Development issued a notice to remind citizens to take precaution.
The statement read, "If the temperature is forecast to reach above 40 C, all outdoor work should be suspended for the whole day, while on days with daily highs between 37 C and 40 C, people should not work outdoors for longer than six hours a day."
Four people died in Hefei, Anhui Province, 16 people in Jiangsu and one in Shanghai because of the heat wave. They were workers in construction sites or senior citizens.
A doctor at the Fengxian District Central Hospital in Shanghai said that "the death rate of heat stroke patients can reach above 30 percent."
Heat stroke occurs when the body reaches temperature beyond 40.6 degrees Celsius as an effect of environmental heat exposure. Symptoms like dizziness, weakening of the body and disorientation may occur. The body fails to manage its internal temperature and sweating stops.
When experiencing a heat stroke, a person must hydrate and find a way to cool down immediately. Lack of response may lead to organ failure and death.