Indian authorities  have ordered schools to shut down early for the summer holiday, after temperatures hit 47.4 degrees Celsius with Delhi gripped by a "severe heatwave".

India's weather bureau has warned of "severe heatwave conditions this week, with the mercury reaching the sizzling peak of 47.4 degrees Celsius in Delhi's Najafgarh suburb on Monday, the hottest temperature countrywide.

Reports have it that authorities in other states including Haryana, Madhya Pradesh, Punjab and Rajasthan, have also ordered schools to close.

Years of scientific research have found climate change is causing heat waves to become longer, more frequent and more intense.

The Indian Meteorological Department warned of the impact of the heat on the health especially for infants, the elderly and those with chronic diseases.

Meanwhile, the next round of voting in India's six-week-long election takes place on Saturday, including in Delhi.

Turnout in voting has dipped, with analysts suggesting the hotter-than-average weather is a factor, as well as the widespread expectation that Prime Minister Narendra Modi will easily win a third term.

India's election commission has formed a task force to review the impact of heatwaves and humidity before each round of voting.

Severe storms also hit parts of the country last week, including in the financial capital Mumbai, where strong winds flattened a giant billboard that killed 16 people and left dozens more trapped.