A sharp increase in heat and humidity levels this summer has led to a significant jump in electricity consumption by Delhi and its people, finds a new analysis by Centre for Science and Environment (CSE). Even though the summer of 2025 experienced fewer heat waves and was relatively cooler than that of 2024, it was a lot ‘wetter’ due to intense rain.
In the pre-monsoon months of March to May, the capital witnessed a moderate heat index range of 31-32 oC – the electricity demand remained stable during these months. With the onset of monsoons (June-August), the range jumped up to 46-50oC. Humidity-driven discomfort levels were very high, leading to increased cooling demand and more electricity consumption.
“As much as 67 per cent of the daily peak electricity demand in Delhi can be explained by variations in heat index compounded by the lowering of adaptive comfort and changing lifestyles, which is increasing the city’s dependence on mechanical cooling systems,” finds the analysis.
Says Anumita Roychowdhury, executive director-research and advocacy, CSE: “Our study shows how an increase in peak electricity demand is now happening earlier and persisting longer. But Delhi’s deadly dilemma is not only the high heat during the pre-monsoon months, but also the high humidity during monsoon months causing sharp increase in heat index (combination of heat and humidity)”.
“This is when the heat index goes beyond the threshold of thermal comfort to surge sharply as cooling devices are switched on across the city. This leads to sharper rise in electricity consumption, which strains grid reliability. Delhi has hit the second highest peak demand for electricity after 2024 summer,” she said.
Roychowdhury adds: “Moreover, warmer nights due to inadequate dissipation of heat accumulated during the day are causing prolonged heat exposure, increasing public health risks. This needs urgent action”.
She said that it is imperative to address growing concretisation, inadequate urban greens and waterbodies, lack of thermal comfort in buildings, inadequate cooling shelters, and waste heat from air conditioners and vehicles. These are making our cities hotter, while climate change is making temperature and humidity trends more erratic, she added.
According to Sharanjeet Kaur, deputy programme manager, urban lab, CSE, “during the monsoon months in 2025, the daytime and nighttime land surface temperatures (LSTs) have risen by about 2.1°C and 3.0°C respectively compared to 2024, while the day-night cooling difference has narrowed down — thus reducing the cooling window. This is adding to the heat distress”.
Notably, April 2025 registered higher electricity consumption than April 2024, reflecting a much warmer start to the summer this year. Kaur says this new assessment is a continuum of CSE’s earlier analyses in 2018, 2019 and 2020, which had also highlighted the impact of heat stress on electricity demand in the city.