In the past month, ENSO-neutral conditions continued, as indicated by near-average sea surface temperatures (SSTs) in the east-central equatorial Pacific Ocean [Fig. 1]. The latest weekly Niño-3.4 index value was +0.4°C, with the westernmost (Niño-4) and easternmost (Niño-1+2) indices at +0.5°C and +1.0°C, respectively [Fig. 2]. The equatorial subsurface temperature index (average from 180°-100°W) increased for the sixth consecutive month [Fig. 3], with widespread, significantly above-average subsurface temperatures across the equatorial Pacific [Fig. 4]. Westerly wind anomalies were observed over the western equatorial Pacific at low levels and were evident over the central and east-central Pacific at upper levels. Convection was near average on the equator near the Date Line and was suppressed around Indonesia [Fig. 5]. Collectively, the coupled ocean-atmosphere system reflected ENSO-neutral conditions.

The North American Multi-Model Ensemble (NMME) average, including the NCEP CFSv2 [Fig. 6], favors El Niño to form by next month and persist through Northern Hemisphere winter 2026-27. While confidence in the occurrence of El Niño has increased since last month, there is still substantial uncertainty in the peak strength of El Niño, with no strength categorization exceeding a 37% chance [Figs. 7 & 8]. The strongest El Niño events in the historical record are characterized by significant ocean-atmosphere coupling through the summer, and it remains to be seen whether this occurs in 2026. Stronger El Niño events do not ensure strong impacts; they can only make certain impacts more likely (see CPC outlooks for probabilities of seasonal anomalies). In summary, El Niño is likely to emerge soon (82% chance in May-July 2026) and continue through Northern Hemisphere winter 2026-27 (96% chance in December 2026-February 2027).