Modi warns of dangers as heatwave grips India

International air-quality monitoring platform AQI recorded that the top 45 hottest cities in the world were all in India at midday on Wednesday, all above 43C.

"Different parts of India are witnessing soaring temperatures, and the challenges that come with it," Modi said.

"This heat is harsh on all of us, and I urge you all to take as many precautions as possible," he said in a statement issued by his office.

Extreme heat can lead to dehydration that thickens the blood and, in particularly severe cases, causes organs to shut down.

At least 16 people died of heatstroke in southern Telangana state last week.

Ignoring warning signs "can quickly turn dangerous and may even lead to heatstroke", Modi added.

"Children, the elderly and those working outdoors are especially vulnerable during extreme heat."

The India Meteorological Department (IMD) on Tuesday recorded the highest temperature of 47.4C in the city of Banda in Uttar Pradesh state, 465 kilometres (289 miles) southeast of New Delhi, 3.8C above normal.

The city hit 48.2C earlier this month.

Temperatures in New Delhi were 40C at midday on Wednesday, according to IMD.

- 'Every drop matters' -

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

Soaring summer temperatures that come before monsoon rains also increase the risk of forest fires.

The Indian army on Wednesday issued photographs of its soldiers, who battled for more than 16 hours to contain a raging blaze near the Himalayan hill town of Kasauli.

Air force helicopters dropped giant buckets of water, which the army said was "decisive in containing the blaze". Firefighting operations continue.

India's IMD also warned about water shortages as the heatwave stretches on.

"From drying rivers and falling groundwater levels to drought and water scarcity, every drop matters," it said on Wednesday, urging people to conserve water.

In addition to searing midday heat, India's minimum temperatures during the night are scorching hot -- giving people little respite.

The country's highest officially recorded temperature is 51C, measured at Phalodi in Rajasthan in 2016.