The persistent heatwave, which has smothered many parts of China for the past week, is set to linger for another week despite this year's 13th solar term of the Chinese traditional calendar, liqiu, or the start of autumn, falling on Sunday.

Liqiu usually marks when temperatures will begin to drop, and the temperature difference between day and night will become greater.

Yet searing heat will continue to scorch the country's many regions, from east to west, especially along the lower reaches of the Yangtze River, around the Sichuan basin and in Xinjiang's Turpan area, with temperatures in parts of the regions expected to exceed 40 C and possibly set new records, the National Meteorological Center announced on Sunday.

The unusual heat will not subdue until mid-August due to the influence of strong subtropical high pressure, said meteorologists.

Even the lowest temperatures will still run high, up to 30 C, in areas around the Yangtze River basin-encompassing megacities from Shanghai on the coast to Chongqing in the interior, according to the forecast by the national observatory.

Shanghai, which is experiencing its third heatwave of the summer, entered its 34th high-temperature day with the mercury rising above 35 C on Sunday.

The city has recorded four days of temperatures exceeding 40 C this summer, including an equal highest temperature since records began in 1873 at 40.9 C on July 13 and the latest on Friday at 40.2 C.

The eastern coastal city with a permanent population of 25 million has seen a significant increase in the number of extremely hot days since 2009, recording 18 days when the temperature passed 40 C since records began. Before 2009 this had only happened twice.

Even with the strong convective weather on Saturday afternoon with hail, pouring rain and gale-force winds, the heat in the city was undeterred, returning on Sunday morning driving the mercury up to 37 C.

The national observatory has advised the public to stay indoors as much as possible and for those who have to work outdoors to take necessary protective measures. Health experts have also cautioned about the risks of heatstroke, while fire security authorities reminded car owners to clear their cars of flammable items such as lighters and hand sanitizers to avoid risks of spontaneous combustion in extreme heat.

Many netizens have posted this phrase on their social media accounts: "This summer, my life hangs on the air conditioner."