Parts of India recorded their highest average temperatures on record in April, and the scorching weather is expected to stretch into May, authorities said on Saturday.

According to a Reuters report, India and neighbouring Pakistan have been suffering from extreme heatwaves this year, melting pavements, forcing school closures and triggering health and fire alerts.

Northwest and central India recorded average maximum temperatures of 35.9 and 37.78 Celsius (96.6 and 100 Fahrenheit) respectively in April, the Director-General of the Indian Meteorological Department told reporters.

Those were the highest since it began keeping records 122 years ago, Mrutyunjay Mohapatra added.

More than a billion people are at risk of heat-related impacts in the region, scientists have warned, linking the early onset of an intense summer to climate change. read more

For the first time in decades, Pakistan went from winter to summer without the spring season, Pakistan’s Federal Minister for Climate Change, Sherry Rehman, said on Saturday.

A record-breaking “heat dome” across north-west India has worsened a severe shortage of coal for power generation and raised the risk of blackouts at hospitals in New Delhi, Financial Times reported quoting government statements.

The heatwave, which has pushed temperatures to more than 45C in places, is forecast to worsen this weekend and ease after May 2, according to the India Meteorological Department.

The high temperatures, which began in March, have driven up power demand from air conditioning units, worsening a critical shortage of the coal that is used to generate power for New Delhi and other nearby cities.

The intense temperatures, from 35 degrees in Mumbai up to 43 degrees in New Delhi, have arrived much earlier than usual, taking the country by surprise and exposing hundreds of millions of people to heat stress, the report added.

“We are seeing many cases of heat exhaustion, dysentery, body ache, and the number of viral fever cases have increased too since the last two weeks,” said Dr Madhav Thombre, a general practitioner based in Mumbai. “This year the heat was severe and came earlier than usual.”

The prolonged heatwave is caused by a stagnant weather pattern or “heat dome”, similar to the one that caused record heat and fires across Canada and the north-western US last year.

According to the Financial Times report, this March was the hottest March in more than a century in north-west India, and April is poised to set records too.

The stagnant weather that drives such a long heatwave is caused by a slowing of the jet stream, according to Zachary Zobel of the Woodwell Climate Research Center in Massachusetts. The jet stream is a fast-moving band of air high in the atmosphere that governs the weather patterns of the northern hemisphere.

As the world warms, heatwaves “are going to get more intense and occur over longer durations”, said Zobel. “There will be parts of the world that will be at times nearly uninhabitable. This is another piece in the data set that is trending in that direction.”

The world has already warmed around 1.1C since pre-industrial times, and is expected to pass 1.5C of warming within the next two decades if current emissions trends continue.