This summer and monsoon season were characterized by fewer heatwaves and more showers. Yet, Delhi’s electricity demand has gone up, according to a new analysis. This high demand can be attributed to a heat index ranging between 46°C and 50°C.
What is the Heatwave Index
The heat index is the “feels-like” temperature shown on weather dashboards along with the actual temperature. It factors in both temperature and relative humidity. As conditions become hotter and more humid, the heat index rises, prompting people to switch on their cooling devices. Air conditioners and coolers are being extensively used to escape heat stress, which in turn is pushing up electricity demand. Monitoring this increase is crucial, as it has become a sensitive marker of the heat stress the region is facing. Even during Delhi’s monsoon season, when days are usually more comfortable, the heat index remained high, further driving cooling demand.
The humid heat became even more unbearable this August compared to last year, leading to higher electricity consumption. According to a policy brief released by the Delhi-based think tank Centre for Science and Environment (CSE), “In August 2025, the average peak demand was about 2% higher compared to August 2024. Nearly half of the days in August 2025 (16 out of 31) recorded higher peak demand than the same days in 2024.”
“August is increasingly behaving like a peak summer month with rising demand loads that stretch the grid beyond its traditional summer stress period,” the report further stated. August has now become hotter, with electricity demand peaking earlier in 2025 compared to 2024.
Researchers also observed a strong correlation between Delhi’s daily electricity demand peaks and the heat index, showing that power demand rises in lockstep with temperature and humidity.
“About 67% of the variation in Delhi’s daily peak electricity demand can be explained by cooling demand, responding to how hot and humid it feels outside,” the report noted.
During the monsoon months of 2025, daytime and nighttime land surface temperatures rose by about 2.1°C and 3.0°C respectively compared to 2024. At the same time, the day-night cooling difference narrowed, reducing the natural cooling window. This added to heat distress. “In April 2025, electricity consumption was already higher than in April 2024, reflecting a much warmer start to the summer season,” said Sharanjeet Kaur, Deputy Programme Manager at CSE’s Urban Lab.
Cooling Demand Rise in Night Time
Another significant trend observed in 2025 was that cooling demand peaked at night (11:09 PM), unlike in previous years when the surge was seen in the afternoon. This shift is linked to a 42% reduction in nighttime cooling in 2025 compared to the 2001–2010 average. Higher nighttime temperatures mean the mercury dips less from day to night, causing greater thermal discomfort and worsening health impacts.
The report highlights the urban climate-energy nexus Delhi is currently facing, where intensifying summer heat and humidity are driving up cooling demand and electricity consumption. The summer season in the capital is no longer defined by predictable curves of temperature and demand, but by volatile interactions of heatwaves, erratic rainfall, humidity, and dependence on mechanical cooling.
The city’s energy consumption response to rising temperatures, humidity, and land surface heating underscores how climate change is reshaping electricity demand. These insights will help in identifying the thresholds of thermal comfort for Delhi’s residents in the future.