Due to the unprecedented burdens on public health, agriculture, and other socio-economic and cultural systems, climate change-induced heatwaves in India can hinder or reverse the country’s progress in fulfilling the sustainable development goals (SDGs). Moreover, the Indian government’s reliance on its Climate Vulnerability Index (CVI), which may underestimate the impact of heatwaves on the country’s developmental efforts. An analytical evaluation of heat index (HI) with CVI shows that more than 90% of the country is at extremely cautious or dangerous levels of adversely impacting adaptive livelihood capacity, food grains yield, vector-borne disease spread and urban sustainability. The results also show by examining Delhi’s urban heat risk that heatwaves will critically hamper SDG progress at the urban scale. Linking HI with CVI identifies more of India’s vulnerability and provides an opportunity to rethink India’s climate adaptation policies through international cooperation in designing holistic vulnerability assessment methodologies. The conclusion emphasizes the urgent need to improve extreme weather impact assessment by combining multiple layers of information within the existing climate vulnerability measurement frameworks that can account for the co-occurrence and collision of climate change events and non-climate structural SDG interventions.