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How ENSO Actually Works — A Developer's Guide to El Nino Data

El Nino Southern Oscillation (ENSO) data is messy. Here's what I learned building a live ENSO tracker widget.

The only number that matters

Nino 3.4 SST anomaly. It's the sea surface temperature deviation in a specific box of the Pacific (5N-5S, 120W-170W). If it's ≥ +0.5C for 3 months → El Nino. ≤ -0.5C → La Nina. In between → Neutral.

Where the data comes from

NOAA publishes OISSTv2 monthly. It's free, but the format is... scientific. NetCDF files, gridded data. You need to extract the Nino 3.4 region and average it.

Why I built a widget

Every climate blog was either embedding a 500KB NOAA chart or just writing "it's an El Nino year." I wanted something lightweight that anyone could drop in:

<iframe src="https://elninoguide.com/widget-embed.html"
  width="300" height="200"></iframe>
Enter fullscreen mode Exit fullscreen mode

Live ENSO badge, dark theme, no dependencies.

Try it: https://elninoguide.com/widget-embed.html
GitHub: https://github.com/dayu2333-jinyul/elnino-climate-data

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