The El Niño Briefing — the archive

Week to October 9, 2026

+3.2 °C, and the odds of a historic event rise to 83%

NOAA's weekly Niño 3.4 reached +3.2 °C for the week centred 30 September, a second record week in a row. CPC's 8 October discussion puts the chance of a historic October–December at 83%, up from 75%.

Week to October 2, 2026

+3.1 °C — the weekly record falls, two months early

NOAA's weekly Niño 3.4 reached +3.1 °C for the week centred 23 September, the highest in a series that starts in 1981. Niño 3 and Niño 1+2 set records the same week; in 1997 and 2015 the same week read +1.8 and +2.0.

Week to September 25, 2026

All 22 models say 'very strong' through the winter

IRI's September outlook: all 22 models forecast a very strong El Niño from autumn through winter, and a majority could reach +3.0 °C or more. Why they agree: subsurface temperatures 50–150 m down exceed normal by more than 8 °C.

Week to September 18, 2026

The warmest September week on record

Niño 3.4 reached +2.9 °C, the warmest September week in NOAA's weekly series and 0.1 °C short of the all-time weekly high. Plus two coral studies on how El Niño has changed over a thousand years.

Week to September 11, 2026

CPC now puts a record event at 75%

NOAA's September outlook raised the odds of a record-breaking El Niño from 69% to 75%. What that asks of the index, compared like for like with 1982, 1997 and 2015.

Week to September 4, 2026

The raw index just set a record for a June–August. The corrected one says +1.4

NOAA's June–August ONI came in at +1.80 °C, the warmest June–August since 1950. The relative index, RONI, reads +1.4: strong, rising, not yet historic.

Week to August 28, 2026

The headline number stalled. The one that matters didn't

Weekly Niño 3.4 went flat at +2.6°C while RONI doubled from +0.5 to +1.0 in one season. Why the gap between the two numbers is the week's real story.

Week to August 21, 2026

Four boxes, one verdict: this is the classic, east-loaded El Niño

Niño 1+2 at +4.0°C while Niño 4 stands still: six weeks of readings have declared which kind of El Niño 2026–27 is — and where its effects will land.

Week to August 14, 2026

The ocean said +2.6°C weeks ago. The atmosphere just voted

MEI.v2 for June–July reads +2.41 — higher than 1997, 2015 or 1982 at the same point. What a record coupling index says about the October–December peak.