Heat crisis deepens in North: Longer spells, rising night temps

Bathinda: India's heat crisis is turning more relentless, more humid, and harder to escape, extending beyond searing afternoons into uncomfortably warm nights. Over the past decade, a clear pattern has emerged — the country's summers are not just getting hotter, but increasingly more hazardous, a new study by research-based consultancy Climate Trends has found.Released on Friday and based on IMD data, the study shows that heatwave frequency across India's core heatwave zone has risen by 0.1 days per decade between 1961 and 2020. The duration of heatwaves in vulnerable regions has increased by 0.44 days per decade. At the same time, average night-time temperatures are climbing by around 0.21°C every decade, with all 35 states and union territories showing a warming trend. Rising humidity is compounding the problem, with average relative humidity increasing from 67.1% in 2015–19 to 71.2% in 2020–24. As human-induced climate change pushes baseline temperatures higher, heatwaves are now beginning from a hotter base and peaking at more extreme levels.The core heatwave zone (CHZ) covers the states of Punjab, Haryana, Himachal Pradesh, Uttarakhand, Delhi, Rajasthan, Uttar Pradesh, Gujarat, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, West Bengal, Odisha and Telangana.According to meteorologists, the ongoing weather conditions are due to the unabated flow of hot north-westerly winds coming from the desert region across Rajasthan, Punjab, Haryana, till central India. Minimum temperatures have also been settling above average, further contributing to heat stress. Most of the night temperatures have been settling in the late 20s, and some stations have also reached 30°C. According to the WHO Housing and Health Guidelines, indoor air temperatures should not consistently exceed 24°C to prevent heat-related health risks, cardiovascular strain, and autonomic disruption during sleep.According to a study by IMD, there is an increasing trend of 0.1 days/decade in the frequency of heatwaves averaged over the core heatwave zone (CHZ) during 1961-2020. Also, the total duration of heatwaves averaged over the CHZ has increased by 0.44 days per decade, with the maximum duration showing an increasing trend of 0.55 days per decade. All the trends are statistically significant. Severe heat waves have also seen an increasing trend in the frequency, total number, and maximum duration in the CHZ.According to the World Meteorological Organization (WMO), 2025 was among the three warmest years ever recorded globally, with global temperatures reaching nearly 1.44°C above pre-industrial levels. The past 11 years, 2015-2025, are the 11 warmest years in all eight datasets."India's heat waves are no longer being driven by temperature alone. What we are witnessing today is a dangerous convergence of rising temperatures, warmer nights, increasing humidity, and rapid urbanisation, all of which are amplifying heat stress across the country. Heat is becoming more prolonged, more humid, and increasingly difficult to escape, especially for vulnerable communities and outdoor workers. These changing weather patterns are a stark reminder that climate change is now reshaping how heat is experienced in India, turning it into a major public health, economic, and development challenge," said Aarti Khosla, founder and director, Climate Trends.