El Niño will 'pour fuel on the fire' as India experiences deadly heatwave

Temperatures have soared across India during an earlier than normal heatwave. (AP Photo: Rajesh Kumar Singh)

Temperatures in India have soared above 45 degrees, sending power usage to record levels as people try to stay cool.

The deadly heatwave has also forced schools to close, people to take days off work, and farmers to work at night.

The United Nations has warned the world to prepare for an El Niño this year, which could worsen drought and heatwaves in some areas and bring heavy rainfall in others.

Afternoon markets have emptied, farmers are working at night, and some schools have closed, with the weather too hot for people to function normally.

But the United Nations has now warned the rest of the world, including Australia, to prepare for a moderate-to-strong El Niño this year, which would make some weather and climate extremes more likely.

The World Meteorological Organization believes the likelihood of El Niño developing by November is "near or above 90 per cent" and that it is expected to be "at least moderate and possibly strong".

"The world must treat it as the urgent climate warning it is," UN chief Antonio Guterres said.

People cool off at a public swimming pool amid a heatwave in New Delhi. (Reuters: Adnan Abidi)

While India is no stranger to heat waves, Dr Soumya Swaminathan told ABC's The World that extreme temperatures recorded across many parts of the country since April began "quite early" and that it's been so hot and humid that even the nights have not cooled down.

"Clearly, the trend over the last few years is that every year we've reached higher temperatures, the heat has been more prolonged and over larger parts of the country," she said.

"The urban areas, the cities even, are facing the brunt even more.

The former World Health Organization (WHO) chief scientist said she believed heat-related deaths had been under-reported in India because it was not easy to diagnose, especially if the person died at home or outside a health facility.

Soumya Swaminathan says there is a need for a national approach and more solutions to heatwaves in India. (By Fabrice Coffrini)

But Dr Swaminathan said heat-related deaths were also just the "tip of the iceberg" of this heatwave's impact.

"[Hot weather] affects a much larger base of ill health, of people not being able to perform, of people not being able to work," she said.

"We also know that women face a disproportionate burden of heat, that domestic violence, for example, goes up during the hottest days of the summer, and they also suffer a lot of physical, reproductive health and