More resources here.
Historical projections from many different models (both physics-based dynamical models and statistical models) with actual observations overlaid in black:
Forecasts from various models going out until October of next year:
For a reference on our ability to forecast ENSO, see Chen et al. They reconstruct forecasts using the LDEO model going back more than a century:
|Time series of SST anomalies averaged in the NINO3.4 region (5° S–5° N, 120–170° W). The red curve is monthly analysis of [reconstructed observations] and the blue curve is the LDEO5 prediction at 6-month lead. Source: Nature.|
and show, somewhat incredibly, that strong El Nino events can be reasonably forecast (corr ~ 0.75) up to twenty months in advance: