Heatwaves in the summer and extreme rainfall in the following summer monsoon season over the same regions in India pose severe challenges for adaptation in agriculture, infrastructure, and public health. However, the risks and drivers of the sequential extremes in India remain unrecognized. Here, we show that the mega-heatwaves in summer and extreme rainfall in the summer monsoons of 1995 and 1998 affected 20% and 8% of India, respectively. The area affected by the sequential extremes is significantly (p < 0.05) higher during the positive phase (El Nino) than the negative phase. The fraction of the total population and urban area exposed to sequential extremes will increase rapidly if the global mean temperature rises above 1.5 degrees C from the pre-industrial level. A considerable improvement in socioeconomic livelihood and infrastructure will be needed to reduce vulnerability and maintain the same level of risk at 1.5 degrees C at higher global warming levels.