The El Niño Briefing #4: The headline number stalled. The one that matters didn't
Updated: August 28, 2026 · 2 min read · Live dashboard
Two numbers moved in opposite directions this week, and the gap between them is the story.
The weekly Niño 3.4 anomaly — the figure that leads the dashboard — went +2.6 → +2.7 → +2.6 °C across the last three weekly updates. Flat, near the top of its range. Read alone it says the event has stopped climbing.
RONI says otherwise. NOAA's relative index, which strips out the background warming of the whole tropical ocean, moved from +0.5 °C (AMJ) to +1.0 °C (MJJ) — it doubled in one season. That is the measure the agency itself leans on when deciding how strong an event really is, because it answers the question the raw number cannot: how much of this is El Niño, and how much is simply a warmer ocean than in 1997?
So: the raw reading is holding near its high, and the El Niño signal underneath it is still strengthening.
Where that leaves the comparison. Under RONI, the three benchmark events peaked at +2.4 (1982–83), +2.3 (1997–98) and +2.3 (2015–16). We are at +1.0. Anyone telling you this is already a record event is reading the raw anomaly against trend-corrected history — two different rulers. On a like-for-like basis 2026–27 is clearly below all three, and still rising.
We changed our own chart this week for exactly that reason. The conventional-index race chart was drawing the 2026 line from one dataset and the historical lines from another, which overstated our position by 0.31 °C at the July reading — and the error grew as the event strengthened. All four lines now come from a single source. The chart shows less of a lead than it did on Thursday, and that is the point.
What to watch. The official outlook still puts the peak at Oct–Dec 2026, with better than 90% odds of a very strong event and roughly 97% that it persists into early spring 2027. The next weekly update lands Monday; NOAA's weekly file is Wednesday-centred, so the 26 Aug reading is the one to look for.
Notes for the owner (not part of the email)
- The 12 Aug weekly reading of +2.7 is the highest of the event so far; 19 Aug eased to +2.6. Worth not calling that a turn — one week is noise.
- The RONI jump AMJ → MJJ (+0.5 → +1.0) is the single strongest fact available this week and is not on the site's homepage prose yet.
- The race-chart paragraph is included deliberately: publishing a correction that makes our own headline less dramatic is the cheapest credibility a data site can buy. Cut it if you would rather not draw attention to it, but it is the strongest paragraph here.
- Nothing in this draft claims a record. Every comparison is RONI-to-RONI.