Some say the weather-altering phenomenon could arrive as early as July and warn that nations typically affected by its weather shifts should prepare for an unusually strong outbreak.
Many El Niño experts have begun to predict that because the warming is developing early in the year, it points to the likelihood of an intense El Niño.
The warming typically begins when warm water near Indonesia spreads eastwards and rises to the surface of the Pacific.
Since warm water promotes rainfall aloft, El Niño robs rain from Australia and Indonesia then dumps it on parts of the Pacific coasts of North and South America.
This often brings drought to Australasia and floods to Peru and California.
If an El Niño becomes established during the next few months, it could also weaken storms in the upcoming Atlantic hurricane season.