The El Niño Briefing #15: NOAA cuts the record odds to about 60%

About 60%. That is NOAA's chance now that this El Niño ends up the strongest since 1950. A month ago it was 83%. The Climate Prediction Center published its November discussion on 12 November, and the cut is the headline. The event itself has not turned. In CPC's words, "El Niño will continue to strengthen before beginning to weaken in early 2027."

This week in one line: Niño 3.4 +3.3 °C · Niño 3 +4.4 °C · Niño 1+2 +5.6 °C · Bureau of Meteorology +2.75 °C · ONI +2.46 °C (Aug–Oct) · RONI +1.97 (Aug–Oct).

Why the odds fell while the ocean stayed hot. CPC's bar for "historic" is a three-month RONI of +2.5 or more. RONI is the relative index: it takes out the warming of the tropical oceans as a whole. For August–October it stands at +1.97, so there is still a gap to close. CPC puts the chance at about 60% for both October–December and November–January (last month: 83% and 70%). The chance that the event stays strong or very strong through January–March is now over 79%, from over 83%. All the numbers from the 12 November update →

The weekly number eased. Niño 3.4 read +3.3 °C for the week centred 4 November, down from +3.4. Off Peru and Ecuador it went the other way: Niño 1+2 reached +5.6 °C, the highest in NOAA's weekly file again. Before this year the best was +4.5 °C, in June 1983. The Bureau of Meteorology's relative Niño 3.4 dipped to +2.75 °C for 2–8 November, from a series high of +2.88 °C the week before.

The same week in 1997 and 2015. +2.2 °C in the week centred 5 November 1997, +2.6 °C in the week centred 4 November 2015.

On the ground: Brazil. Brazil's government El Niño panel (INMET, INPE, Cemaden, the water agency ANA, the geological service SGB, civil defence and Censipam) issued its fifth bulletin on 29 October. From November to January it favours above-average rain in the South and below-average rain across much of the North and parts of the Northeast and Centre-West. Southern rivers are already high, with flooding in parts of the Uruguay, Taquari and Caí basins; the geological service has issued more than 270 hydrological alerts for the region this year. In the Northeast, drought is spreading: on partial October data Cemaden counted 68 municipalities in extreme drought, against 4 in August. Temperatures should run above normal almost everywhere, most of all in the North, except Rio Grande do Sul, where the panel expects cooler than normal weather. There, the wet spell may slow the wheat harvest and soybean sowing, though it helps maize and pasture. How El Niño plays out in Brazil →

A note on privacy. On 11 November we updated the privacy policy for two things: the new Guess Monday game, which stores the nickname you type, your guess and a random ID your browser keeps; and Monday alerts, which can now also announce a new record, still at most one notification a day.

Next. NOAA's weekly file updates on Monday 16 November with the week centred 11 November. CPC's seasonal outlook for the US winter is due on 19 November, and the next ENSO discussion on 10 December.

Live dashboard → · Live map → · Event log →

— The El Niño Briefing