Assessment of outdoor thermal comfort in Northwestern India using effective temperature (ET) and the temperature-humidity index (THI).

Authors

Tanmay Sanjay Jadhav, Amit Gulabrao Dhorde

Published in

International journal of biometeorology. Volume 70. Issue 8. Jul 23, 2026. Epub Jul 23, 2026.

Abstract

Understanding long-term and intra-annual variations in human thermal discomfort is essential for climate-health assessments in climate-sensitive regions. In this paper, thermal comfort dynamics have been analyzed at seven locations in Northwestern India by utilizing Effective Temperature (ET) and Temperature-Humidity Index (THI) data for a period of 54 years (1969-2022). Climatic data for dry-bulb temperature (DBT), wet-bulb temperature (WBT), relative humidity (RH), and wind speed (WS) on a daily basis were acquired from the India Meteorological Department (IMD), while missing data were supplemented from NASA's MERRA-2. Analyses were conducted at annual, seasonal, monthly, and weekly scales. Annual averages of ET and THI indicate generally comfortable conditions; however, higher-resolution analyses reveal substantial thermal stress periods that annual means obscure. At Delhi and Amritsar, ET shows either weak or non-significant trends, while THI exhibits significant warming due to increased WBT, reduced RH, and wind stilling. Trends analyzed on a monthly and weekly basis reveal pronounced seasonal intensification of heat stress. During the pre-summer period, ET shows notable warming, with weekly trends reaching + 0.081 to + 0.086 °C/year in Ambala and Patiala. Pre-monsoon warming is more evident in THI, increasing by + 0.058 to + 0.077 °C/year during mid-May in Delhi, Patiala, and Amritsar. Persistent peak heat from June to mid-July coincides with WBT increases of approximately + 0.05 °C/year at several stations. In contrast, winter and post-monsoon periods exhibit cooling in THI associated with reductions in WBT and DBT, while ET shows weaker declines due to concurrent decreases in wind speed. These contrasting ET and THI responses highlight the importance of multi-index and ventilation-sensitive assessments for thermal risk evaluation, public health preparedness, and climate adaptation planning in Northwestern India.

PMID:
42489935
Bibliographic data and abstract were imported from PubMed on 23 Jul 2026.

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