Christopher W. Corwin

I hold a Bachelor of Science in Meteorology from Northern Illinois University. I built IAMElNino.com, I write and edit everything published on it, and I maintain the data pipelines behind the dashboard. It is an independent project, run by one person, and it is not affiliated with NOAA, NASA, the Bureau of Meteorology, the WMO or any other agency.

I am not an operational forecaster and I do not issue forecasts. Nothing on this site is an official outlook. What I do is read the primary ENSO data as it is published, calculate the comparisons that agencies do not publish directly, and explain what the measurements support and what they do not.

Why This Site Exists

In February 2026 NOAA's Climate Prediction Center changed the index its ENSO products quote, moving from the conventional Oceanic Niño Index to the Relative Oceanic Niño Index. Australia's Bureau of Meteorology had adopted parallel relative indices the previous September. The change matters: the two indices can differ by close to a degree in a warm tropical year, and NOAA continues to publish weekly tables on both conventions at the same time.

Most coverage did not track that change. Numbers from the relative and conventional tables were quoted interchangeably, which produced apparent "revisions" that were nothing of the kind. I built this site to follow the index CPC actually uses, publish the conventional value alongside it, and say clearly which is which. The difference between RONI and ONI and why CPC and IRI publish different Niño 3.4 numbers are the two pieces that set that out.

How I Evaluate Primary-Source Data

• The agency file, not the press release. Weekly Niño-region values come from CPC's own text tables, seasonal RONI and ONI from CPC's index series, MJO from NOAA PSL. Where an article quotes a figure, the file it came from is linked.
• The index label travels with the number. Niño 3.4 is not Niño 1+2, a relative index is not a conventional one, a weekly value is not a three-month seasonal mean, and none of them is global mean temperature. Conflating these is the most common error in ENSO coverage.
• Data vintage is stated, not implied. Weekly values are centred on a date rather than ending on one, and NOAA revises recent seasonal values for up to two months. Articles say which week or season a value refers to.
• Observation, model output and forecast probability are kept apart. A model count is not a probability, an analog score is not a forecast, and a probability is not an observation.
• Claims carry a failure condition. Most articles state what specific, dated evidence would confirm or refute them. If a claim cannot be made falsifiable, that is usually a sign it should not be published.

What I Focus On

• Relative versus conventional ENSO indices, and why two official numbers for the same ocean disagree
• East-west structure across the Niño regions, and what it says about event flavour
• Ocean-atmosphere coupling: whether the atmosphere is actually responding to a warm Pacific
• The MJO's role in accelerating or stalling ENSO development
• Historical analogs, their inputs and weights, and the ways they break
• Tracing widely repeated figures back through their syndication chain to the original agency source

Representative Work

• Why CPC and IRI publish different Niño 3.4 numbers Traces two conflicting official figures back to their source files and shows why both are correct.
• The east-west gradient between Niño 1+2 and Niño 3.4 Original calculation of the basin gradient from the weekly CPC table, with a chart built from the cited data.
• Verifying CPC's own ENSO forecasts against what happened Scores past published probabilities against subsequent observations rather than restating the current outlook.
• A correction: what the drought risk figures actually measured A published account of an error on this site, what caused it, and what was withdrawn as a result.
• A monthly 2°C reading is not the Paris threshold Separates a single monthly anomaly from the multi-decade average the Paris Agreement refers to.

Editorial Accountability

The rules I hold myself to are written down rather than implied, and errors are logged in public rather than quietly edited.

Contact

Corrections are welcome and are the fastest way to improve the site. A pointer to the specific figure, the page it appears on and the source you believe is correct gets it fixed quickest.