Millions of people were hard hit by an early summer heatwave across India and Pakistan on Thursday, leading to power and water shortages as annual furnace-like temperatures hit South Asia.

This was made even worse where in New Delhi, a burning rubbish dump choked residents for a third day with temperatures crossing 45 Celsius (113 Fahrenheit) in parts of South Asia on Thursday several degrees higher than normal and forecasters warning that it will get even hotter this weekend.

Heatwaves have killed over 6,500 people in India since 2010, and scientists say climate change is making them harsher and more frequent across the region.

"This is the first time I've seen such horrible weather in April. Usually, we're prepared for this in May and onwards," said 30-year-old Delhi housewife Somya Mehra, as she and her family thirstily searched for a cold drink.

"Today we stepped out because of our anniversary but otherwise I'm not stepping out at all. I've stopped sending my kid out to play".

The Indian states of Rajasthan, Gujarat and Andhra Pradesh imposed power cuts on factories as consumption for air conditioning and fans skyrocketed.

Media reports said that power stations were also facing shortages of coal -- the main source of electricity in the nation of 1.4 billion people.

Many regions also reported falling water supplies that will only worsen until the annual monsoon rains in June and July.

Water shortages will hit farmers hardest, including those growing wheat as India aims to boost exports to help ease a global shortage due to the war in Ukraine.

Temperatures are expected to be up to eight degrees higher than usual in parts of Pakistan, with the mercury peaking at 48 degrees in parts of rural Sindh on Wednesday, Pakistan's Meteorological Society warned.