Asian summer monsoon (ASM) rainfall is life blood for over 60% of the world population, yet seasonal prediction of this variability remains a long-standing challenge. Analysis of the 1979-2009 rainfall variability over the entire Asian monsoon and Indo-Pacific warm pool reveals that the variability of the ASM precipitation originates from four principal processes, which account for about 50% of the total summer rainfall variability: (a) a forcing from the central Pacific seas surface temperature (SST) anomalies often associated with the developing La Nina or central pacific El Nino, (b) a positive thermodynamic feedback between ASM circulation and underlying Indo-Pacific ocean dipole (IPOD) SST anomalies (warming in the northern Indian Ocean and cooling in the western North Pacific), (c) an interaction between ASM and Indian Ocean dipole (IOD) SST, and (d) the effect of global warming. Evidence also shows that the IPOD coupled mode became substantially weakened after the late 1990s, whereas the IOD mode has been steadily intensified over the last two decades. The predictability of these precipitation modes is investigated in terms of multi-coupled AOGCM's hind cast experiments. The most prominent weakness is the models' failure in capturing the IPOD coupled mode.