A 64-year-old Taiwanese man died of heat stroke in Shanghai yesterday, raising the city's death toll from the heat wave to at least 11, authorities said.

Heat claims another victim to take Shanghai toll to 11.[File photo]

Forecasters said the high temperatures are likely to continue until the middle of this month before temperatures are expected to drop to about 35 degrees Celsius.

Until then, the city will have to endure at least another 10 days of temperatures ranging from 38 to over 40 degrees, the Shanghai Meteorological Bureau said.

The Taiwanese boatman, who arrived in Shanghai on July 13 to carry out repairs on his ship, fainted on July 23 and was taken to Shanghai Longhua Hospital for emergency treatment, local border inspection authorities said.

His condition deteriorated throughout the week and he died yesterday morning from organ failure, the hospital said.

The Shanghai Center for Disease Control and Prevention said that about a third of the city's fatalities had fallen sick even though they had been indoors, but gave no further details.

Three people died of heat stroke despite emergency treatment at the Minhang District Central Hospital within the past week.

Renji Hospital said it had treated 15 patients for heat stroke so far. Four were in critical condition when they were admitted and three had died despite emergency treatment. The other patient who was in a critical condition has since recovered and had been allowed home.

Some doctors advised senior citizens to switch their air conditioning on, dismissing a widely held belief among the elderly that air conditioning is unhealthy.

Yesterday's maximum temperature was 39.8 degrees Celsius — the 25th straight day of temperatures above 35 degrees. On Tuesday, the city broke its previous record of 23 high-temperature days set in July 1934.

Thunderstorms in some parts of the city yesterday brought temperatures down slightly, but forecaster Man Liping said: "Rain and thunderstorms are likely in parts of the city in the afternoon but any relief from the heat is likely to be short-lived."

Shanghai's weather authority has no plans to manufacture artificial rainfall to cool the high temperatures. Artificial rainfall will pose problems for flights taking off and landing, and there is the possibility of injury from falling material used to seed the clouds.

Neighboring cities of Hangzhou, Ningbo and Nanjing cities have created artificial rainfall in the past three days to bring some relief from the soaring heat.

Hangzhou has become China's hottest city. Since last Tuesday, the air temperature has exceeded 40 degrees Celsius on six days.

That's the hottest period recorded in Hangzhou since records began 62 years ago.

Shanghai's weather bureau has warned seniors, pregnant women and people suffering chronic diseases, especially cardiovascular ailments, to refrain from going outside between 10am to 4pm, the hottest time of the day.