Delhi witnessed one of its most severe heatwave episodes this summer, with temperatures soaring to 50 degrees Celsius. June also recorded the city's warmest night in two years. Rising humidity, prolonged heatwaves and increasingly unpredictable weather patterns across the country are intensifying extreme heat even before the monsoon fully establishes itself.
According to the latest weather outlook, scorching summer conditions are expected to persist for the next three days across parts of Uttar Pradesh, Uttarakhand, Himachal Pradesh, Ladakh and southeast Rajasthan.
The worsening heat stress in Delhi is being driven by multiple interconnected factors. Global climate change has made heatwave conditions more frequent and intense. At the same time, the Urban Heat Island effect has significantly raised temperatures in densely populated urban areas, where temperatures can be up to 8 degrees Celsius higher than surrounding rural regions. Experts project that this difference could increase to 9 degrees Celsius by 2050.
The rapid loss of green spaces and water bodies has further reduced the city's natural cooling capacity by limiting shade and evaporation. Closely packed buildings, inadequate ventilation and insufficient shaded areas have intensified heat retention throughout the capital. Air pollution also contributes by reinforcing heat, while expanding infrastructure, urbanisation and rising carbon dioxide emissions continue to compound the effects of climate change.
The growing demand for cooling reflects these changing conditions. Global cities have experienced an increase of approximately 1.12 percent in cooling demand over the past 20 years. In several Indian cities, cooling is now required for nearly 273 days each year as higher temperatures persist for longer periods.
Humidity has emerged as another critical factor affecting thermal comfort. High moisture levels increase the perceived temperature by influencing latent heat, making conditions feel significantly hotter than the actual air temperature. Eastern coastal Indian cities experience the country's highest cooling demand, estimated at 2,514 ± 224 degree Celsius-years, due to the combined impact of consistently high temperatures and elevated humidity.
Rapid urbanisation is accelerating the warming trend across India's major cities. The construction of taller buildings restricts airflow, trapping heat within densely developed areas. In cities such as Delhi and Kolkata, limited land availability has encouraged vertical expansion while replacing green spaces with roads and concrete structures that absorb and retain more heat. The widespread use of air conditioners further contributes by releasing waste heat into the surrounding environment.
Night-time temperatures are also rising across Delhi and other urban centres. The Urban Heat Island effect has made cities approximately 60 percent hotter than non-urban areas. Large-scale atmospheric conditions, often described as heat domes, trap warm air over cities for extended periods. Pollution and increased atmospheric moisture also contribute by altering heat retention, while water vapour acts as a greenhouse gas that further raises temperatures.
The consequences of extreme heat are becoming increasingly severe across India. Prolonged exposure to high daytime and night-time temperatures places significant physiological stress on the human body and increases the risk of heat-related illnesses, including heatstroke and hyperthermia. Elderly people, young children and outdoor workers remain among the most vulnerable groups.
Agriculture is also facing mounting challenges. Crops such as rice and wheat are highly sensitive to extreme temperatures, with prolonged exposure beyond thermal thresholds reducing productivity. Temperatures above 35 degrees Celsius can trigger physiological damage in plants, resulting in sterile pollen, aborted embryos and lower nutritional value.
The livestock sector is equally affected, as excessive heat reduces appetite among cattle and poultry. Poultry mortality can increase to as much as eight times the normal average during periods of intense heat, adding further pressure on food production and rural livelihoods.
As India continues to confront longer, hotter and more frequent heatwaves, Delhi's record-breaking temperatures underscore the growing impact of climate change, rapid urbanisation and environmental degradation. With the delayed arrival of the southwest monsoon, the country's capital has become a stark example of how rising temperatures are reshaping public health, agriculture, infrastructure and everyday life.
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