Hundreds of millions of people in India and Pakistan will not have any respite from the blistering heat that has gripped the subcontinent for several weeks, pushing electricity demand to breaking point and straining water supplies.
Daytime high temperatures will continue in the first week of May in India, along with warmer nights, the country's weather office predicted.
Experts are warning failure to take precautions, such as avoiding prolonged exposure to heat, could result in fatalities.
India’s meteorological department said large parts of north-western, western and central India experienced the hottest April in over a century as mercury breached the average monthly temperature by several notches.
“April was the fourth-hottest month in the country ever,” Mrutyunjay Mohapatra, director general of India’s Meteorological Department, said at a press conference on Saturday.
Forecasters have issued warnings of extremely high temperatures and warmer nights in most parts of the country, except some regions in south peninsular India.
A dozen states in north, west and central India will continue to reel under high temperatures, including Uttar Pradesh, Haryana, Delhi, Punjab, Rajasthan and Madhya Pradesh.
“Most parts of north-west India are expected to experience above-normal temperatures in May,” Mr Mohapatra said.
There are predictions that parts of western Rajasthan state could experience a temperature of 50°C (122F) in May.
“Since May is the warmest month of the year, areas of western Rajasthan can touch 50°C…we are expecting increased temperature in western parts,” he said.
A brutal heatwave has been sweeping across large swathes of India since March — a time that often sees pleasant spring weather — owing to “scanty” rainfall, according to the IMD.
According to the IMD, a heatwave is a weather condition when the maximum temperature breaches the 40°C mark in low-lying areas and 30°C in higher terrain.
March this year, with an average temperature of 33.1°C, was the hottest March in recorded history since 1901.
On Saturday, temperatures hovered around 43.5°C in the capital New Delhi — the second-hottest April in the last 72 years.
There is a possibility of a thunder and dust storm over the city on Monday, but the heatwave is likely to continue in the city and neighbouring regions for the next three days.
New Delhi has experienced three prolonged heatwaves in April because of the absence of light rainfall and thunderstorms.
Hundreds of millions of people are at risk because of the unusual weather, with health experts warning people to avoid direct heat exposure.
More than 6,500 people have died between 2010-18 due to heatwaves, according to government data.
Severe water and electricity shortages in some parts of the country have added to the misery of the population, amid reports of a crippling coal crunch to run thermal power plants.
The intense heat has caused forest fires and left several rubbish dumps ablaze across the country, including one in New Delhi.
Some 300 forest fires were reported at the end of April, with almost a third in the Himalayan state of Uttarakhand.
Weather experts have attributed the record heatwave to the absence of periodic light rainfall due to the lack of rain storms coming from a weather system known as the Western Disturbance. The system emanates from the Mediterranean Sea and brings moisture-rich clouds to the subcontinent.
“It is rare. We can attribute this weather phenomenon to climate change and global warming,” Mahesh Palawat, vice president of the private weather forecaster, Skymet Weather, told The National.
Pakistan has also been in the grip of extreme heatwave, with several parts of the country recording a record high temperature of 47°C (116.6F) on Saturday.
Jacobabad was the hottest place with a record of 49°C.
Sindh and Punjab regions have also been facing a severe heatwave. In Karachi, mercury hit 40°C on Saturday. The metropolis had recorded the hottest night in April since 2010 on Friday.
The government has urged authorities to take precautionary measures to manage the intense heatwave.
The country is also facing an acute energy crisis, worsened by prolonged power outages amid increased power demand.