Understanding the underlying dynamics of the Indian summer monsoon (ISM) extremes such as severe droughts is key to improving seasonal prediction of the ISM rainfall. A large number of ISM droughts over the past century occurred unrelated to
external forcing like the El Niño–Southern Oscillation (ENSO). In this study, we challenge the perception that the 2009 ISM drought was driven by ENSO and show that it was caused by internally driven processes.

Reliable medium range prediction of monsoon weather is crucial for disaster preparedness. Weather in tropics, controlled by fast growing convective instabilities is, however, intrinsically less predictable than that in extra?tropics.