^+2c by September, which the mean Euro is predicting, has only been done twice since 1950 (1997 +2.1, and 2015 +2.2). They were the two strongest El Nino's at a later peak since 1950 (ONI).
If you adjust -0.5 for the RONI, +2c by September would be the 8th strongest El Nino on record.