A thunderstorm appeared to have helped spare Shanghai from breaking its 40.9C record on Saturday, though residents of the commercial hub of 25 million still expressed fatigue from the ongoing heatwave.

"It's like being in a steamer, it's really hot," said 70-year old resident Shen Fengming. "Even if you don't walk around outside, you'll still end up sweating."

"I went to our port and walked around," said 45-year-old Huang Yi, who works at a container port. "It was just an hour, but my clothes and pants were all wet. Compared to years before, the temperature this year is particularly high."

On Saturday Shanghai's meteorological observatory reported that the city has seen 40 days with temperatures exceeding 40C this year, peaking so far on 13 July at 40.9 degrees.

Last week China's weather bureau warned that the country's average ground temperatures had risen much more quickly than the global average over the past 70 years and would remain "significantly higher" in the future as the challenges of climate change mount.

Much of Europe has seen weeks of baking temperatures, with wildfires raging in France and parts of England facing a severe drought, as successive heatwaves renewed the focus on climate change risks.