The Met Office has predicted that day temperatures in Karachi are likely to rise to 40° Celsius today.
Temperatures are likely to hover between 41 and 42 degrees Celsius today, the meteorological department said.
Winds from the northwest, according to the meteorological report, sharply increased temperatures and the intensity of extreme weather.
This heat wave is likely to continue for the next two days.
Experts advise the general public to avoid unnecessary exposure to direct sunlight and to use water and cold drinks wisely.
Global temperatures hit record highs last year and the UN World Meteorological Organization said Asia was warming at a particularly fast pace, with the impact of heat waves in the region becoming more severe.
Scientific research has shown that climate change is making heat waves longer, more frequent and more intense.
