Delhi’s electricity demand rises despite milder summer, driven by high heat index.
Cooling demand peaks at night due to higher temperatures at night, impacting health.
Urban heat island effect intensifies thermal stress, raising overall electricity consumption.
Delhi’s electricity demand has flared up despite a summer with lesser heatwaves, according to a policy brief by Delhi-based think tank Centre for Science and Environment (CSE).
Heat index is the “feels like” temperature, capturing both relative humidity of a place along with temperature. Due to increased humidity in the monsoon months, people turn to their cooling devices, such as air conditioners or coolers, to escape heat stress. This pushes up the electricity demand.
The high electricity demand seeped into monsoon months during June and August as well due to the high heat index in that range of 46-50 degrees Celsius.
Monitoring electricity demand is important because it has become a sensitive marker of heat stress.
During Delhi's monsoon months that were comparatively wetter this year than earlier, the heat index shoots up, dragging along the cooling demand.
“In August 2025, the average peak demand was about 2%higher compared to August 2024, despite wetter conditions this year. Nearly half of the days in August 2025 (16 out of 31) recorded higher peak demand than the same days in 2024.”
The researchers also observed a strong correlation between daily electricity demand peak and heat index. This means, power demand rises in lockstep with temperature and humidity. The report stated that 67% of the daily peak electricity demand in Delhi’s can be explained by variations in the hot and humid conditions outside.
Another notable trend in 2025 was that peak cooling demand shifted to night (11.09 pm) compared to the afternoon surges observed in previous years. The CSE report attributes this to a 42% reduction in night cooling compared to the 2001-2010 average. A higher night-time temperature implies that the mercury dip from day to night is smaller, increasing thermal discomfort at night and impact on health.
Night-time Heat Drives Demand
Rising night-time electricity peaks in Delhi indicating a worsening urban heat island effect, where city temperatures warm significantly faster than surrounding rural areas.
A 2024 study from the Indian Institute of Technology Bhubaneshwar showed that nearly 60% more night-time warming in over 140 prominent Indian cities was recorded compared to non-urban areas surrounding them. This intensifies thermal stress at night, driving up cooling needs and electricity demand.
Urbanisation is known to be responsible for the urban heat island (UHI) effect, in which the concrete and asphalt (used in constructing roads and pavements) surfaces store heat during the day and release it in the evening, thereby raising night-time temperatures.
Over time, this heat further affects other aspects of climate, including rainfall and pollution, researchers said in the study published in the journal Nature Cities.
(With inputs from PTI.)
