Spatiotemporal changes in heat stress exposure in India, 1981-2023

India is amongst the most susceptible regions in the world to extreme heat stress because of climate change. In this study, we present a comprehensive analysis of the spatiotemporal evolution of heat stress exposure (HSE) across India's districts, which serve as the primary administrative units below the State level. Our analysis covers a long temporal duration (1981-2023) and uses data with high spatial (0.1°) and temporal granularity (hourly). By focusing on the district, we ensure that our findings are relevant for policymakers. We find a 3.3% increase in the average HSE duration across districts when comparing 1981-1995 and 2011-2023. We provide evidence for variation in the evolution of HSE by time of day, time of year, and across regions in India. We also provide estimates of changes in outdoor occupational exposure from 2019-2023. Our research highlights the importance of considering HSE in addition to average temperature changes and has important implications for public health practitioners and policymakers.