It appears we were right to close out the 2014-15 El Niño Series last week. NINO1+2, NINO3, and NINO3.4 region weekly sea surface temperature anomalies are below the +0.5 deg C threshold of El Niño conditions, and the NINO4 region temperatures are getting closer to the threshold.
The NINO3.4 (5S-5N, 170W-120W) sea surface temperature anomalies haven’t remained elevated long enough for this season to register as an El Niño on the NOAA Oceanic NINO Index (ONI).
The JMA uses NINO3 region (5S-5N, 150W-90W) sea surface temperature anomalies as their reference. According to the JMA webpage here:
JMA defines that the El Niño (La Niña) is such that the 5-month running mean SST deviation for NINO.3 continues +0.5ºC (-0.5ºC) or higher (lower) for six consecutive months or longer.
Right now, the 5-month running mean of NINO3 sea surface temperature anomalies has been above 0.5 deg C for 5 months. We’ll have to wait until the January data are posted to find out if JMA considers an El Niño took place in 2014.