It's not skewed by anything. If Nino 3.4 was +0.6, it's x0.6 weight. If Nino 3.4 was +3.0, it's 3.0x weight. If Nino 3.4 was -2.0, it's -2.0x weight.
Also, Nino 1+2 is currently +2.6. Here is June-July of Nino 1+2:
It's following the ENSO script about as closely as it can imo