028
FXUS24 KWNC 091301
PMDENS
El Nino/Southern Oscillation (ENSO) Diagnostic Discussion
NWS Climate Prediction Center College Park MD
900 AM EDT Thu 09 Oct 2025

NOTE: figures mentioned in the discussion are available on
the internet at HTTP://WWW.CPC.NCEP.NOAA.GOV

ENSO Alert System Status: La Nina Advisory

Synopsis: La Nina conditions are present and favored to persist
through December 2025 - February 2026, with a transition to
ENSO-neutral likely in January-March 2026 (55percent chance).

La Nina conditions emerged in September 2025, as indicated
by the expansion of below-average sea surface temperatures
(SSTs) across the central and eastern equatorial Pacific Ocean
(Fig. 1). The latest weekly Nino-3.4 index value was -0.5degC,
with other regions remaining at or between -0.1degC and -0.4degC
(Fig. 2). Negative subsurface temperature anomalies persisted
(averaged from 180deg-100degW; Fig. 3), with below-average
temperatures prevailing from the surface to 200m depth in
the eastern half of the equatorial Pacific (Fig. 4). Over the
western and east-central equatorial Pacific, low-level wind
anomalies were easterly and upper-level wind anomalies were
westerly. Convection continued to be enhanced over Indonesia
and was suppressed near the Date Line (Fig. 5). The equatorial
Southern Oscillation index was positive. Collectively, the
coupled ocean-atmosphere system reflected La Nina conditions.

The IRI multi-model predictions favor La Nina through
the Northern Hemisphere winter 2025-26 (Fig. 6). The North
American Multi-Model Ensemble is also in agreement, and based
on recently observed anomalies, the team favors La Nina to
continue through winter. At this time, La Nina is expected to
remain weak (3-month average Nino-3.4 index value at or between
-0.5degC and -0.9degC). A weak La Nina would be less likely
to result in conventional winter impacts, though predictable
signals could still influence the forecast guidance (e.g., CPC`s
seasonal outlooks). In summary, La Nina conditions are present
and favored to persist through December 2025 - February 2026,
with a transition to ENSO-neutral likely in January-March 2026
(55percent chance; Fig. 7).

This discussion is a consolidated effort of the National Oceanic
and Atmospheric Administration (NOAA), NOAA`s National Weather
Service, and their funded institutions. Oceanic and atmospheric
conditions are updated weekly on the Climate Prediction
Center website (El Nino/La Nina Current Conditions and Expert
Discussions). A probabilistic strength forecast is available
here. The next ENSO Diagnostics Discussion is scheduled for
13 November 2025. To receive an e-mail notification when the
monthly ENSO Diagnostic Discussions are released, please send
an e-mail message to: ncep.list.enso-update@noaa.gov.



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