Nearly two-thirds of India sizzled under a spell of a heatwave that is on course to becoming the longest ever as scalding temperatures killed four train passengers, drained water supplies, and drove thousands of tourists to hill stations already bursting at the seams.

Across large swathes of northern, central and peninsular India, the mercury breached the 45 degree mark, including in Jhansi in Uttar Pradesh, Churu and Bikaner in Rajasthan, Hisar and Bhiwani in Haryana, Patiala in Punjab, and Gwalior and Bhopal in Madhya Pradesh.

The Capital, which sweltered on its hottest June day in history on Monday (48 degrees Celsius) recorded as maximum temperature of 45.4 degrees Celcius at Palam in spite of a spell of light rain in the morning.

Experts warned that monsoon relief was still some time away with the severe cyclonic storm, Vayu, barrelling towards the Gujarat coast and drawing rain clouds from over the sea.

With a heatwave spell stretching 32 days, 2019 has already seen the second-longest spell of scorching temperature ever recorded. If the mercury doesnt dramatically drop in the next two days, 2019 will become the year with the longest heatwave spell in recorded history with three weeks to go in June.

In 1988, there were 33 such days, and in 2016, there were 32 such days.