NEW DELHI — One of India’s longest and most intense heat waves in decades, with temperatures reaching 123 degrees, has claimed at least 36 lives since it began in May, and the government has warned that the suffering might continue as the arrival of monsoon rains has been delayed.

India’s heat waves have grown particularly intense in the past decade, as climate change has intensified around the world, killing thousands of people and affecting an increasing number of states. This year, the extreme temperatures have struck large parts of northern and central India, with Rajasthan, Madhya Pradesh, Uttar Pradesh and Maharashtra among the worst-hit states.

Anup Kumar Srivastava, an expert at India’s National Disaster Management Authority, said the number of Indian states hit by heat waves had grown to 19 in 2018 from nine in 2015, and was expected to reach 23 this year.

“This year, the number of heat wave days have also increased — and it’s not just day temperature, night temperatures have also been high,” he said.