An elderly sailor from Taiwan died of multiple organ failure triggered by heatstroke on Wednesday morning, the latest victim of the unprecedented summer heat scorching the Chinese business hub.

The 64-year-old sailor, surnamed Zeng, began his ship inspection and repair work on July 13 and showed serious symptoms of heatstroke 10 days later, according to the Jinshan branch of the Shanghai General Station of Exit and Entry Frontier Inspection.

Zeng's condition deteriorated on Tuesday. He died early Wednesday morning at a Shanghai hospital.

Over 10 people have died of heatstroke in Shanghai this month, local health officials said Tuesday.

The Shanghai Municipal Center for Disease Control and Prevention said the persisting high temperatures this summer have caused a spike in the number of heliosis patients in the city.

Temperatures in Shanghai surpassed 39 degrees Celsius on Wednesday, the ninth straight day for temperatures to rise above 38 degrees Celsius, the Shanghai Meteorological Center said.

The center said that with 25 days of temperatures at or above 35 degrees Celsius monitored so far, this July has been the hottest for Shanghai since weather records started 140 years ago.