A new study by Climate Trends, a research consultancy, has revealed that India's heat crisis is intensifying, becoming more relentless, humid, and inescapable. The analysis, based on India Meteorological Department (IMD) data, shows that heatwaves are not only scorching afternoons but also dangerously warm nights, with the past decade exhibiting a clear trend of increasingly hazardous summers.
Key Findings on Heatwave Trends
The study indicates that the frequency of heatwaves across India's core heatwave zone (CHZ) has increased by 0.1 days per decade from 1961 to 2020. This translates to roughly one-tenth of a day more of heatwave conditions each decade. Additionally, the duration of heatwaves in these prone regions has grown by 0.44 days per decade, with the maximum duration rising by 0.55 days per decade. All these trends are statistically significant.
Rising Night-Time Temperatures and Humidity
India's average night-time temperatures are increasing by approximately 0.21°C per decade, with all 35 states and union territories showing warming trends. Concurrently, average relative humidity has risen from 67.1% during 2015–2019 to 71.2% in 2020–2024. Human-caused climate change is elevating baseline temperatures, causing heatwaves to start from a hotter background and reach higher peaks.
Core Heatwave Zone (CHZ) States
The CHZ encompasses Punjab, Haryana, Himachal Pradesh, Uttarakhand, Delhi, Rajasthan, Uttar Pradesh, Gujarat, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, West Bengal, Odisha, and Telangana.
Current Weather Conditions
Meteorologists attribute ongoing conditions to the unabated flow of hot north-westerly winds from desert regions across Rajasthan, Punjab, Haryana, and central India. Minimum temperatures have been settling above average, contributing to heat stress. Most night temperatures remain in the late 20s Celsius, with some stations reaching 30°C. According to the World Health Organization (WHO) Housing and Health Guidelines, indoor air temperatures should not consistently exceed 24°C to prevent heat-related health risks, cardiovascular strain, and sleep disruption.
Expert Insights
Mahesh Palawat, Vice President of Meteorology and Climate Change at Skymet Weather, explained that the absence of weather systems over the Indian mainland allows hot northwesterly winds from Pakistan's Sindh region and Rajasthan to penetrate deep into the country. The uninterrupted flow over three to four days has pushed mercury to severe heatwave levels. He noted that high daytime temperatures, combined with a lack of pre-monsoon evening activities, lead to elevated nighttime temperatures. Relief is expected only with the arrival of a western disturbance, which will alter wind patterns.
Aarti Khosla, Founder and Director of Climate Trends, emphasized that India's heatwaves are no longer driven solely by temperature. She highlighted a dangerous convergence of rising temperatures, warmer nights, increasing humidity, and rapid urbanization, all amplifying heat stress. Heat is becoming more prolonged, humid, and difficult to escape, especially for vulnerable communities and outdoor workers. These changing patterns underscore that climate change is reshaping heat experiences in India, posing major public health, economic, and development challenges.
Global Context
The World Meteorological Organization (WMO) reports that 2025 was among the three warmest years on record, with global temperatures reaching nearly 1.44°C above pre-industrial levels. The past eleven years (2015–2025) are the eleven warmest in all eight datasets.
