New Delhi, Sept. 9 -- Delhi recorded unusually high heat index levels this monsoon, driven by elevated humidity despite relatively lower temperatures, leading to a surge in power demand, according to an analysis by the Centre for Science and Environment (CSE) released on Monday. The study found that 67% of the variation in Delhi's daily peak electricity demand is now attributable to the combined impact of heat index and cooling needs. While the pre-monsoon months of March to May registered moderate heat index values of around 31 to 32degC and relatively stable power use, the monsoon months of June to August saw a dramatic spike, with the index crossing the 46 to 50degC mark. CSE's executive director for research and advocacy, Anumita Roycho...