The South American rainfall Dipole (SAD) is a renowned spatial structure
present in the austral summer as part of the South American monsoon
system. SAD phases have been related with extreme precipitations and
severe droughts across South America, but are yet to be predicted. Here,
we reveal $2$ robust and reliable intraseasonal windows in the
accumulated SAD index where we can forecast its quantile-state between
$5$ to $15$ and $60$ to $70$ days in advance
($99\%$ significance level). These windows are
insensitive to variations in the pole’s size and accumulation window,
and results are consistent across different quantiles states (median,
tercile, and quartile). Our method, which is based on analysing the
lagged mutual information between future and present states, could be
used in the development of early-warnings for extreme rainfall events.
Moreover, it is unrestricted to the present analysis, being applicable
to other stationary signals where a forecast is missing.