Towards the Development of a Comprehensive Heatwave Proneness Index and Identification of Hotspots Across Indian Mainland

Abstract Heatwaves (HWs) are one of the key‐emerging climatic hazards, with increasing duration, severity, and frequency all over the globe. Identifying HW‐prone regions and their evolving patterns is therefore essential for effective climate adaptation. To address this, we introduce the “Heat‐Wave Proneness Index (HWPI),” a novel metric to identify the key‐exposed regions or hotspots by integrating three key HW attributes—(a) the maximum annual HW magnitude, (b) the mean HW magnitude excluding the maximum (MeanX), and (c) the annual frequency (Frq) of HW events. By applying HWPI across the Indian mainland, we demonstrate its superiority to capture diverse regional variations in HW‐exposure more effectively than one of the widely‐used HW‐indices—Heat‐Wave Magnitude Index daily (HWMId). Further to validate the reliability of the proposed index, top 10 HW‐affected years are identified across India since 1951, out of which four are found from the recent past decade (2010–2019) itself. A comprehensive spatiotemporal analysis is also conducted using the proposed HWPI, over the historical (1951–2020) and future (2021–2050) periods, which reveals the western, central, north‐eastern and western peninsular India to be the most HW‐prone regions in the country. India as a whole will experience approx. two‐fold increase in HW‐ proneness toward mid‐century relative to the 1981–2010 baseline, as depicted from the multi‐model multi‐scenario analysis. Overall, we expect the newly proposed HWPI and visual identification of the future‐projected HW‐prone regions will not only be useful to the scientific community but also for the policymakers to build climate‐informed decisions sufficiently in advance.