El Niño is favored to form in the next couple of months and continue through the Northern Hemisphere winter 2018-19 (70-75% chance).

ENSO-neutral continued during September, but with increasingly more widespread regions of above-average sea surface temperatures (SSTs) across the equatorial Pacific Ocean.

Over the last month, all four Niño index values increased, with the latest weekly values in each region near +0.7C (Fig. 2). Positive subsurface temperature anomalies (averaged across 180°-100°W) also increased during the last month, due to the expansion and strengthening of above-average temperatures at depth across the equatorial Pacific.

The majority of models in the IRI/CPC plume predict El Niño to form during the fall and continue through the winter. The official forecast favors the formation of a weak El Niño, consistent with the recent strengthening of westerly wind anomalies and positive temperature trends in the surface and subsurface ocean. 

Click here to read the complete ENSO report from NOAA