I think we already are in an El Niño. We're doing that crazy cycle of cool and rainy for a couple of days, which then starts to warm and become humid, then one stupidly hot day where the temp jumps 5-10 deg from the previous day (hot winds optional depending on where you are), then a thunderstorm and we're back at the beginning again. That's the weather patten (for Wollongong anyway) that I tend to associate with us being in an El Niño.