ElNinoLive

Where every number comes from

Nothing on this site is our own measurement. We fetch, parse and chart primary data from NOAA and NASA, name the source under every chart, and show you when a number was last refreshed. This page is the full audit trail.

Sources & update cadence

Weekly Niño-region SST anomalies

Data as of July 3, 2026

Weekly sea surface temperatures and anomalies for Niño 1+2, 3, 3.4 and 4 (OISST v2.1, 1991–2020 climatology). Drives the headline number, gauge and status.

Cadence: Fetched daily; NOAA updates weekly (Mondays) · Source: https://www.cpc.ncep.noaa.gov/data/indices/wksst9120.for

Oceanic Niño Index (ONI), 1950–present

Data as of July 3, 2026

NOAA’s official ENSO yardstick: three-month running mean of Niño 3.4 anomalies (ERSSTv5). Drives the historical chart and event classifications.

Cadence: Fetched weekly; NOAA updates monthly · Source: https://www.cpc.ncep.noaa.gov/data/indices/oni.ascii.txt

Monthly Niño 3.4 long series

Data as of July 3, 2026

Monthly anomalies used for the 1982-83 / 1997-98 / 2015-16 trajectories in the race chart.

Cadence: Fetched weekly · Source: https://www.cpc.ncep.noaa.gov/data/indices/detrend.nino34.ascii.txt

Southern Oscillation Index (SOI)

Data as of July 3, 2026

Standardized Tahiti−Darwin pressure index — the atmospheric half of ENSO. The Australian Bureau of Meteorology blocks automated access, so we use NOAA CPC’s series (the spec’s designated fallback).

Cadence: Fetched weekly; NOAA updates monthly · Source: https://www.cpc.ncep.noaa.gov/data/indices/soi

Official ENSO outlook probabilities

Data as of June 12, 2026

Seasonal probabilities and advisory status from the NOAA CPC / IRI monthly outlook. Transcribed by hand after each ENSO Diagnostic Discussion because the advisory page isn’t machine-readable.

Cadence: Manual, monthly (~2nd Thursday) · Source: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/

SST anomaly map imagery

GHRSST MUR sea surface temperature anomaly tiles served by NASA EOSDIS GIBS (daily imagery, ~2-day latency), over a Blue Marble base layer. Rendered client-side with Leaflet; dates selectable for the last 30 days.

Cadence: daily · earthdata.nasa.gov/gibs

Methodology notes

  • Intensity bands. Niño 3.4 anomaly below 0.5°C is neutral; 0.5–0.9 weak; 1.0–1.4 moderate; 1.5–1.9 strong; 2.0°C and above very strong. The current reading is +1.8°C.
  • The race chart aligns events by calendar month (January of the onset year through June of year two). Historical lines use the CPC monthly Niño 3.4 series; the 2026 line uses monthly means of the weekly readings, because the monthly file lags — months with fewer than three weekly values are omitted. Climatology baselines differ slightly between the two files (roughly a tenth of a degree), which we accept for a comparison chart and note here.
  • Caching and fallbacks. Data is fetched server-side and cached (daily for weekly SSTs, weekly for the long series). If NOAA is unreachable, bundled snapshots render instead and an amber “cached data” badge appears — the site never shows a blank chart. Every API response carries fetchedAt and isFallback.
  • Probabilities are transcribed by hand. The official outlook is published as prose and graphics, not a feed. We transcribe the headline numbers after each monthly outlook; per-season splits between the headline anchors are editorial interpolations until the next official table, and the file records the outlook date.
  • Open JSON feeds. The parsed data behind this site is public: /api/enso/status, /api/enso/weekly, /api/enso/oni, /api/enso/soi, /api/enso/race and /api/enso/probabilities. Please cache responses and attribute NOAA as the underlying source.

Disclaimers

We are an independent project, not affiliated with NOAA, NASA or any weather service. Seasonal forecasts are probabilistic: they tilt odds, they do not promise outcomes. For warnings and life-safety decisions, use your national meteorological service. Definitions follow NOAA usage; Australia's BOM applies slightly different thresholds, which is why declarations sometimes differ between agencies.

Questions about the data? Get in touch — corrections are welcome and published visibly.