Climate change is likely to affect both the short-term variability of water resources through increased frequency and intensity of droughts and floods, and long-term changes in mean renewable water supply. Both models and historical data suggest that temperatures have increased in most parts of India, affecting the hydrologic cycle through decreased Himalayan snowpack, increased evaporation, and evapotranspirative demand by vegetation. In contrast, there are uncertainties about the climate–rainfall relationship. While most climate models predict intensification of the Indian monsoon, past rainfall trends suggest a weakening and a regional redistribution, perhaps due to local factors such as aerosols, land use change, and sea surface temperatures. Translating these uncertain projections to water availability is complicated by sparse hydrologic records and human modifications of catchments. Empirical research suggests that climate change is not the only stressor. As climate and socio-economic futures are interlinked, this requires participatory, adaptive management and mainstreaming of adaptation across agencies.