OREANDA-NEWS   China’s most populous city, Shanghai, has issued its highest alert for extreme heat for the third time this summer as sweltering temperatures repeatedly tested records this week.

The commercial and industrial hub of 25 million people declared a red alert on Thursday, warning of expected temperatures of at least 40C (104F) in the next 24 hours. Temperatures soared as high as 40.6 C in the afternoon but fell short of Wednesday’s 40.9 C, which matched a 2017 record.

Extreme heat conditions have also taken hold in parts of Europe. Firefighters have been battling wildfires in Spain, Portugal, France and Croatia.

As of 5pm local time, Shanghai’s red alert was in force. The highest of a three-tier colour-coded warning system, it requires construction and other outdoor work to be reduced or halted.

Shanghai has issued three red alerts in the past five days, though these are a relatively rare occurrence, with just 17 issued since record-keeping began in 1873.

The hot weather coincided with mass testing for Covid-19 in several districts amid minor outbreaks, adding to heat woes for both residents and health workers wearing protective suits.

Some Covid-19 testers taped bottles of frozen mineral water to their white hazmat suits as they worked, while others sat next to huge blocks of ice to cool off. “This suit is terribly hot,” Peng Lei, who worked at one testing site, told Reuters. “The clothes are never dry. All day long they are wet with sweat.”

Some communities also began testing in the evening, when it was cooler.

The past month’s unusually hot spell has affected half of China. The Yangtze River basin, encompassing large cities from Shanghai to Chongqing in the heartland, has broiled in heatwaves over the past week.

By 5pm, 86 red alerts had been declared across China, most in the Yangtze basin.

Higher demand for air conditioning pushed China’s maximum power load to an all-time high on Tuesday. Authorities said they were making every effort to ensure energy supplies during the summer’s peak demand period.

In Europe, some countries have been suffering from a second heatwave in as many months.

In south-west France on Thursday, about 1,000 firefighters were battling to control two wildfires that have already burned almost 4,000 hectares. “Since the start of the year, 15,000 hectares have been burned in the country, versus a little less than 1,000 hectares at the same date last year … nine fires out of 10 have a human cause,” France’s interior minister, G?rald Darmanin, told reporters on Wednesday night.

Thousands of firefighters also battled more than 20 blazes that raged on Wednesday across Portugal and western Spain, menacing villages and disrupting tourists amid a heatwave that pushed temperatures above 45C (113F)in some parts of the region.

In Croatia, authorities have been deploying aircraft, dozens of firefighters and soldiers in an effort to contain three major wildfires along the country’s Adriatic coast.

The World Meteorological Organisation warned on Tuesday that a heatwave was spreading and intensifying in large parts of Europe. With human-caused climate change triggering droughts, the number of extreme wildfires was expected to increase 30% within the next 28 years, according to a February 2022 UN report.