BEIJING - As many as 21 provinces and regions in China are baking under a scorching heatwave even as the south reels from devastating floods which killed at least 50 people and forced 1.6 million to flee their homes.

A heat wave will expand from northern China to the central and eastern regions in the coming three days, reported state media. As much as one-third of China's land mass will be affected.

Maximum temperatures in 31 counties and cities in Xinjiang, Ningxia, Gansu, Shaanxi and Sichuan have hit record highs. The Chinese city of Xi'an in Shaanxi saw ground temperatures hitting as high as 50 deg C on Monday (July 10), according to a report on news portal Sina.

Temperatures at Xinjiang's Turpan Flaming Mountain, or Huo Yan Shan as it is famously known in the Chinese classic Journey to the West, have been above 40 deg C for the past 13 days, reported state media.

The city of Turpan saw temperatures hitting a historic high of 49 deg C on July 10 while the township of Erbaoxiang saw the mercury rising above the 50 deg C mark.

Apart from the Xinjiang region, Shaanxi, Gansu and Hebei provinces have experienced many days of extreme heat, with temperatures hovering between 35 and 41 deg C.

The southern parts of the country, which were battered by summer floods recently, will also be experiencing very hot weather that could last from four to nine days, said Mr Sun Jun, chief weather forecaster of the National Meteorological Center.

Some places like Beijing may get some relief this weekend, with temperatures forecast to drop below 35 C.

While the heatwave is making people feel uncomfortable, it is not particularly severe compared to other years, like in 2013, Mr Sun added.

Mr Gu Chengdong, deputy director of the emergency department at China-Japan Friendship Hospital in Beijing, warns the young and old to avoid or cut down outdoor activities.

He suggests reducing time outdoors, especially during the hottest time of the day from 10am to 3pm.

Heatstrokes can happen when the body temperature hits 40 deg C and may lead to organ failure, he added.