“He came through the door and said I can’t deal with this hot weather,” Adnan Zafar, Wasim’s cousin, told the BBC. “He asked for a glass of water. Soon after he finished it, he collapsed.”
By the time Wasim’s family got him to hospital, the medics said he had already died of a suspected heart attack.
He had an existing heart condition, Adnan says, but he hadn’t suffered in the heat before.
Karachi’s struggle to cope with the high temperatures is, some fear, being made worse by regular power cuts which cut off the fans and air conditioning many rely on to keep cool.
Muhammad Amin was among those who was suffering with loadshedding – where the electricity supply was cut off; a common practice across Pakistan by the electricity board to try to preserve supply.
His relative says their flat experienced consistent constant power cuts.
According to his family, Muhammad who was in his 40s suddenly became sick, then died.
Cause of death has not been established, but his family suspect it was heat-related.
According to Dawn newspaper, almost 30 people have been found dead by emergency services on the city’s streets.
Many are suspected drug addicts, Police Surgeon Summaiya Syed told the newspaper. They did not, however, have any signs of injury.
Karachi is not the only part of Pakistan that is struggling to cope.
Last month, the province of Sindh – of which Karachi is the capital – recorded an almost record-breaking temperature of 52.2C, according to Reuters.
Pakistan’s neighbours have been suffering from extreme, deadly temperatures in recent weeks as well.
Across the border in India, the capital Delhi has been enduring an “unprecedented” heatwave, with daily temperatures crossing 40C (104F) since May, peaking at nearly 50C.
Doctors in the city say they’ve never seen anything like it before.
For Karachi resident Mohammad Zeshan, it is clear what the problem is.
“This is due to climate change,” he told Reuters. “This is happening all around the world. This is happening in Europe. They have faced intense heat but they have taken steps about it.
“But here, it is sad that government has not taken any effective measures.”
Experts agree these sorts of extreme weather events are becoming more frequent and intense as a result of climate change.
The heatwave roasting Karachi is expected to last into next week, albeit with slightly lower temperatures forecast.
Weather experts are now turning their attention to the monsoon season, which is expected to arrive early and bring as much as 60% more rain, according to experts who spoke to Dawn.