The temperatures during the day are likely to increase gradually in most parts of the country due to high pressure that develops in the upper atmosphere, said the Met Office.

Karachi will witness hot and humid weather with a temperature between 36 to 38 degrees Celsius during the stated time period, according to an alert issued by the Provincial Disaster Management Authority.

The heatwave will likely hit interior Sindh, with temperature in Dadu, Nawabshah, Jacobabad, Larkana and Sukkur will increase by 48 degrees Celsius, while Badin, Tharparkar, Umerkot and Hyderabad will witness 43 to 45 degrees Celsius temperature.

In upper and central Sindh, South Punjab and parts of Balochistan, the temperature is likely to remain six to eight degrees Celsius above normal, while it is expected to be five to seven degrees Celsius above normal in upper Punjab, Islamabad, Khyber Pakhtunkhwa, Gilgit-Baltistan and Kashmir.

The Met department advised farmers to manage crop water supplies accordingly. It issued an advisory for the public to avoid unnecessary exposure to direct sunlight.

In 2015, a heatwave coincided with power outages and Ramazan, killing 1,300 people from dehydration and heatstroke across the country. After three years, the same weather conditions (44 degrees Celsius) caused 65 deaths in Karachi alone, according to a Reuter's report.