Equatorial Pacific monitor

Daily ENSO state, warm-water volume, the Indian Ocean Dipole and Atlantic genesis windows — every number with its baseline stated, and a public forecast record (2 open).

Niño 3.4+2.95°C
very strong El Nino

observed 2026-09-18
bulletin 2026-09-20 16:27 UTC

Surface

Niño 3
+3.81°C
Niño 4
+1.02°C
Niño 1+2
+4.82°C
Niño 3 − Niño 4
+2.79°C
90-day running mean
+2.37°C

A proxy for the ONI, not the ONI.

OISST anomalies against the PSL 1991–2020 day-of-year climatology

nino34_run is a 90-day running mean — a proxy for the ONI, not the ONI. The official index is a 3-month running mean of monthly ERSSTv5 anomalies.

Subsurface

Warm water volume
+27.36×10¹⁴ m³
WWV anomaly
+1.46×10¹⁴ m³
Mean 20 °C depth
+142.99m
Zonal tilt (west − east)
+2.98×10¹⁴ m³

anomalies against the mean of the accumulated record

A short, moving baseline: it shifts as the record grows, so the same day can carry a different anomaly after a longer backfill. For quotable numbers use PMEL's, in wwv_pmel_monthly.

Indian Ocean Dipole

DMI
+0.97K
30-day mean
+0.46K
West box
+1.16K
East box
+0.19K

dmi_run is a 30-day running mean — a daily proxy for a monthly published index. For anything quoted use BoM's or NOAA's.

Genesis windows 1 open

BoxVI7-dayShearSSTState
ATL_CARIB0.239+0.08421.729.3 °Cclosed rising
ATL_GOM0.045-0.0248.730.8 °Copen falling
ATL_MDR0.175+0.04817.328.6 °Cclosed rising
ENP0.069+0.02211.730.2 °Cclosed rising

Atlantic genesis windows (ERA5 2026-09-14, 7-day means, about 6 days behind today)

opens below VI 0.060, closes above 0.080; genesis very unlikely above about 0.1

shear anomaly baseline: 1991-2020 (20+ years/day)

Figures

Niño indices

Daily values and the 90-day running mean.

Recharge oscillator phase portrait

Anticlockwise is a complete ENSO cycle.

Equatorial Hovmöller

Wind, sea level, isotherm depth, SST and OLR anomalies.

Subsurface temperature section

Absolute temperature with the 20 °C isotherm; no anomaly baseline involved.

Warm water volume against PMEL

Two independent estimates of the same quantity.

Atlantic genesis windows

Ventilation index against the thresholds that open a window.

Today’s bulletin

# ENSO daily bulletin - 2026-09-20 16:27 UTC

Latest observation: 2026-09-18
  Nino 3.4   +2.95 C   -> very strong El Nino
  Nino 3     +3.81 C
  Nino 4     +1.02 C
  Nino 1+2   +4.82 C
  Nino 3 - Nino 4  +2.79 C (east-Pacific leaning)
  90-day running mean  +2.37 C (ONI proxy)

  change over 1 week: -0.00 C
  change over 1 month: +0.38 C

Indian Ocean Dipole (DMI, 2026-09-18):
  DMI  +0.97 K -> positive IOD   30-day mean +0.46 K
  west box +1.16 K, east box +0.19 K
  a daily proxy for a monthly published index; quote BoM or NOAA

Subsurface (recharge state):
  mean 20 C isotherm depth    143.0 m   (west 153.0, east 132.2)
  warm water volume           27.36 x1e14 m3  (anom +1.46, short baseline)
  thermocline contrast         20.8 m (west - east; climatology 80-100 m)
     vs record mean            -1.9 m (short baseline)
  volume tilt (west - east)   +2.98 x1e14 m3  (+1.71 of it is box-width geometry, leaving +1.27)

Atlantic genesis windows (ERA5 2026-09-14, 7-day means, about 6 days behind today):
  box             VI      7d   shear     SST   state
  ATL_CARIB    0.239  +0.084    21.7   29.3C   closed (rising)
  ATL_GOM      0.045  -0.024     8.7   30.8C   OPEN (falling)
  ATL_MDR      0.175  +0.048    17.3   28.6C   closed (rising)
  ENP          0.069  +0.022    11.7   30.2C   closed (rising)
  opens below VI 0.060, closes above 0.080; genesis very unlikely above about 0.1
  shear anomaly baseline: 1991-2020 (20+ years/day)

Standing predictions (issued before the outcome, graded after):
  [2026-09-19] discharge_onset: verify after 2027-07-16
  [2026-09-19] centroid_migration: verify after 2027-01-17

Sources:
  olr   ok (2026-09-06 -> 2026-09-19)
  wwv_check agree (r=+0.99, offset 24.46)
  consistency ok (4 checks)
  forecast 0 issued, 0 graded