Past versions of the vulnerability indices have shown the ability to detect susceptible regions by assessing climatic and socioeconomic parameters at local scales. These parameters significantly vary over geographic regions, therefore such an index may not be suitable to identify and predict susceptibility over a large domain. The present endeavour aims to develop a new vulnerablity index that identifies and predicts the spatiotemporal imprint of extreme drought and flood cases at various scales in India by analyzing monthly observed and Coupled Model Intercomparison Phase 5 (CMIP5) rainfall data at a spatial scale of 1° × 1° from 1901 to 2100. It is proposed by consolidating the outcomes of the Standard Precipitation Index (SPI) at different time scales, such as 3 and 12 months, along with the weights of individual grids. The weights of individual grids are calculated through the occurrence of extreme drought and flood years in the recent past to include a climate change factor in the proposed index. Based on the spatial distribution of high index values, the vulnerable regions concerning extreme droughts are expected to be in the Northeast, Northeast-central, East-coast, West, Northwest, North-central and some grids in South India. Similarly, vulnerable regions concerning extreme flood cases are likely to be in the Northeast, West-coast, East-coast and some grids in the Peninsular region. Furthermore, a conceptual model is presented to quantify the severity of extreme cases. The analyses reveal that on the CMIP5 model data, 2024, 2026–2027, 2035, 2036–2037, 2043–2044, 2059–2060 and 2094 are likely to be the most prominent extreme drought years in all India monsoon rainfall and their impacts will persist for a longer time than others. Similarly, the most prominent extreme flood cases are likely to occur in the year 2076, 2079–2080, 2085, 2090, 2092 and 2099.