Over 400 people have died in a heatwave in the southern province of Sindh, while the rest of the country is also grappling with severe heat.
The deaths come a month after neighbouring India suffered the second deadliest heatwave in its history, with more than 2,000 deaths.
The Islamic fasting month of Ramazan, during which devout Muslims abstain from all food and drink during daylight hours, began on Friday, coinciding with what is usually the hottest time of year in Pakistan.
The Sindh provincial government has imposed a state of emergency at all hospitals, cancelling leave for doctors and other medical staff and increasing stocks of medical supplies.