Evolution of Climate Extremes Over the Indian Subcontinent Using a Revised CEI

Abstract

Employing observed gridded daily rainfall and temperature datasets for 1971–2022, we developed a revised India Climate Extremes Index ( IndCEI ) to assess long‐term variability in climate extremes across the country. The IndCEI modifies the original CEI framework by integrating seven indicators particularly relevant to the Indian climate system: maximum temperature ( T max ), minimum temperature ( T min ), consecutive dry days (CDD), heavy precipitation events, the Standardised Precipitation–Evaporation Index (SPEI), Heat Index (HI), and Excess Heat Factor (EHF). Results reveal robust and widespread warming signals over India, with significant increases in T max extremes across all four homogeneous regions. Northwestern India (NWI) emerges as the principal hotspot, exhibiting the strongest positive trends in T max , HI, and EHF—indicative of intensifying heat stress and more frequent heatwaves. South Peninsular India (SPI) also shows marked increases in drought‐related extremes (SPEI, CDD). In contrast, Northeast India (NEI) displays heightened short‐duration heavy rainfall events alongside increasing drought episodes, signalling greater hydroclimatic variability. East‐Central India (ECI), the core monsoon zone, presents weaker or inconsistent trends, likely reflecting the influence of monsoon variability and embedded low‐pressure systems. Spatial analyses indicate that both T max and T min extremes have expanded beyond localised pockets, while drought and HI extremes have intensified and spread inland from coastal areas‐creating new hotspots in central and eastern India. At the all‐India scale, IndCEI exhibits a statistically significant increasing trend (~0.36% of area per decade), driven primarily by rising heat stress and drought indicators. Overall, the findings highlight a growing risk of climate extremes, particularly heat, drought, and rainfall across India. The results underscore pronounced regional contrasts: western and southern India are increasingly dominated by heat‐related stress, while Northeastern India faces rainfall‐driven extremes. These expanding hotspots of climate stressors call for region‐specific adaptation strategies, particularly addressing heat in NWI, drought in SPI, and rainfall variability in NEI.

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