Over the past several decades south Asian continents has found several droughts and floods. In spite of devastating frequent droughts and floods in the regions, our understanding on weather and climate variability is limited. Present book covers the exhaustive investigations of rainfall variability over south Asian regions and contribute substantially to the fundamental understanding of the climate variability. Ocean warming/cooling near landmass has a significant role on ecosystem. In recent decades, the sea surface temperature of all the major oceans has warming trend which leaves its impact on rainfall and circulations. This book well described the dynamics of anomalous changes in the India Ocean (IO) starting from the southern subtropical IO to the northern tropical IO including south equatorial IO, Arabian Sea, Bay of Bengal, South China Sea and also during dipole events in the IO. This book covers not only observed results but also Regional Climate modelling results. Regional Climate Model well described the sensitivity of sea surface temperature anomalies (over Indian Ocean, Bay of Bengal, Arabian Sea and South China sea) to monsoon circulation and seasonal rainfall.