This month a heatwave has killed over 1500 people in Pakistan, most of them in Karachi. Here are the temperatures recorded at Karachi airport at that time: note that the average for this time of year is 28-35°C with high humidity. Rarely does the temperature reach 39.5°C three days in a row but here it did so six days in a row plus there seemed to be no relief at night.
Most of the dead were homeless and it was also during the time of Ramadan where fasting is observed during daylight hours. This and the recent heatwave in India are two of the three most fatal on the Indian subcontinent in recent times.
 Temperatures: http://www.ogimet.com/cgi-bin/gsynres?lang=en&ind=41780&ano=2015&mes=6&day=30&hora=6&min=0&ndays=30  Average Weather For Karachi, Pakistan – WeatherSpark  Dr. Jeff Masters’ WunderBlog: Pakistan’s Deadliest Heat Wave on Record Kills at Least 800: Weather Underground  News: Majority of Karachi heatwave victims were homeless minister – The Express Tribune