2026 ENSO Updates

[Kingarabian]

FYI the PDO tends to warm during winter and early spring periods. Regardless of phase. But it would be a big step if we can see an actual positive reading soon.

According to NOAA, the pdo has actually gone further negative since December. January recorded a monthly reading of -1.19 vs -0.98 back in December:

https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

Whether this changes for Febuary remains to be seen, but the waters off Japan have been relentlessly warm for the past several years which has made any transition to a proper +pdo difficult.

Yeah the stripe of warmth emanating from Japan is definitely muddling things a bit. We'll have to see if that fades eventually, then we'll likely start to see the PDO index approach positive levels.

Fwiw the CanSIPS, NMME and seasonal Euro actually show the "warm blob" persisting despite +PMM arising. It's a bit of a strange look, could continue to weigh the PDO index down if that's the case.
https://i.imgur.com/LSYr3xf.png
https://i.imgur.com/QFEc5SI.png
https://i.imgur.com/DSaobF2.png

Maybe something similar to 2023. A negative PDO due to the warm Japan waters but we still see an El Nino.

[DorkyMcDorkface]

According to NOAA, the pdo has actually gone further negative since December. January recorded a monthly reading of -1.19 vs -0.98 back in December:

https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

Whether this changes for Febuary remains to be seen, but the waters off Japan have been relentlessly warm for the past several years which has made any transition to a proper +pdo difficult.

Yeah the stripe of warmth emanating from Japan is definitely muddling things a bit. We'll have to see if that fades eventually, then we'll likely start to see the PDO index approach positive levels.

Fwiw the CanSIPS, NMME and seasonal Euro actually show the "warm blob" persisting despite +PMM arising. It's a bit of a strange look, could continue to weigh the PDO index down if that's the case.
https://i.imgur.com/LSYr3xf.png
https://i.imgur.com/QFEc5SI.png
https://i.imgur.com/DSaobF2.png

Maybe something similar to 2023. A negative PDO due to the warm Japan waters but we still see an El Nino.

Yeah I ultimately don't think it will significantly impede the transition to El Niño in the end. We're still well on track for one, the subsurface warmth/downwelling KW is too obvious to ignore at this point.

[Kingarabian]

Looks like a substantial IO WWB in the forecast. Will be key to see it transition to the MC and the WPAC. CFS shows supports this in the MJO charts.

[cycloneye]

CPC weekly update of 2/9/26 has niño region 3.4 at -0.9C.

https://www.cpc.ncep.noaa.gov/products/ ... ts-web.pdf

[Iceresistance]

I think the La Nina is almost dead

https://s12.gifyu.com/images/bke7A.png

[cycloneye]

The PDO factor.

 https://x.com/cyclonicwx/status/2020184495882932455

Due to these latest anomalies, I’ll be a little surprised if January’s PDO index results don’t flip to positive, even if it's just slightly. We should find out on this forthcoming Monday morning around 10AM.

And even if it does trend positive over the next couple of months, I’m beginning to have some doubts about what the atmospheric response will be for my region later this year going into 2027 even if we can achieve a +PDO/+ENSO combo later on this year after some of the discussions between Ntwx and USTropics a few pages back.

Still the january data has not come out in this site.

https://oceanview.pfeg.noaa.gov/erddap/ ... e?time,PDO

[869MB]

The PDO factor.

 https://x.com/cyclonicwx/status/2020184495882932455

Due to these latest anomalies, I’ll be a little surprised if January’s PDO index results don’t flip to positive, even if it's just slightly. We should find out on this forthcoming Monday morning around 10AM.

And even if it does trend positive over the next couple of months, I’m beginning to have some doubts about what the atmospheric response will be for my region later this year going into 2027 even if we can achieve a +PDO/+ENSO combo later on this year after some of the discussions between Ntwx and USTropics a few pages back.

Still the january data has not come out in this site.

https://oceanview.pfeg.noaa.gov/erddap/ ... e?time,PDO

Interesting stuff, because NOAA has clearly has updated their PDO chart with the -1.19 value for January 2026. https://www.ncei.noaa.gov/access/monitoring/pdo/

[cycloneye]

The RONI may alter things with the data about ENSO.

 https://x.com/EliotJacobson/status/2020943710557700393



 https://x.com/BenNollWeather/status/2021045716584702454

[DorkyMcDorkface]

Due to these latest anomalies, I’ll be a little surprised if January’s PDO index results don’t flip to positive, even if it's just slightly. We should find out on this forthcoming Monday morning around 10AM.

And even if it does trend positive over the next couple of months, I’m beginning to have some doubts about what the atmospheric response will be for my region later this year going into 2027 even if we can achieve a +PDO/+ENSO combo later on this year after some of the discussions between Ntwx and USTropics a few pages back.

Still the january data has not come out in this site.

https://oceanview.pfeg.noaa.gov/erddap/ ... e?time,PDO

Interesting stuff, because NOAA has clearly has updated their PDO chart with the -1.19 value for January 2026. https://www.ncei.noaa.gov/access/monitoring/pdo/

Random observation but I never realize how low the index got last summer, it tanked to -4.21 in July! (lowest on record)

[cycloneye]

Well, the other site updated today with January PDO at -0.85.



https://oceanview.pfeg.noaa.gov/erddap/ ... e?time,PDO

[869MB]

Well, the other site updated today with January PDO at -0.85.

https://i.imgur.com/AsbCI1V.jpeg

https://oceanview.pfeg.noaa.gov/erddap/ ... e?time,PDO

Ok well that’s very interesting…So why the discrepancy with the two indexes?

[cycloneye]

Every new updated frames of this loop has the yellows and oranges expanding more and more.

[cycloneye]

Very long post by Dr Ben Noll about the RONI measurment of ENSO and the difference with the ONI.

 https://x.com/BenNollWeather/status/2021607661318369579



@BenNollWeather
There’s a new weather term in town that you'll want to get to know: Relative Niño Index!

As the world warms and sea temperatures rise, traditional monitoring methods for El Niño and La Niña are being supplemented with new techniques that are better suited to deal with that change.

The new term is the Relative Oceanic Niño Index (RONI), which compares ocean temperatures in the equatorial Pacific with the rest of the global tropics to determine how relatively warm or cool one area is compared to another. As the coverage of above-average ocean temperatures increases, it’s becoming more challenging to decipher what’s unusual and what’s not.

This new method helps forecasters better understand where tropical thunderstorms will be focused — which ultimately influence jet streams, high- and low-pressure cells and weather around the world.

NOAA recently announced a shift to this new index to monitor and forecast El Niño and La Niña: https://weather.gov/media/notification/ ... ve_ONI.pdf

Government climate agencies in Australia and New Zealand announced in 2024 and 2025 that they would be using this new index as part of their operational monitoring of El Niño and La Niña — becoming the first countries in the world to make such a change.

These shifts demonstrate that a changing global climate affects more than just air temperatures, rainfall and humidity, also leaving an imprint on the planet’s most significant drivers of climate variability — El Niño and La Niña.

Looking at February's forecast of the relative vs. traditional Niño 3.4 Index, we can see that while the traditional index switches to El Niño by May, the relative index lags behind.

This is because the global tropics are anomalously warm and are predicted to become even warmer — which mutes the El Niño signal in a relative sense.

I'll be referencing both the traditional and relative indices to help with forecasting, but ultimately the new relative indices should be better at detecting the onset and significance of impacts from El Niño and La Niña.

[cycloneye]

Breaking News

Big update and change from CPC with the RONI data.

 https://x.com/NWSCPC/status/2021947407643406449



https://www.cpc.ncep.noaa.gov/products/ ... disc.shtml

In summary, a transition from La Niña to ENSO-neutral is expected in February-April 2026 (60% chance), with ENSO-neutral likely persisting through the Northern Hemisphere summer (56% chance in June-August 2026)

[mixedDanilo.E]

Breaking News

Big update and change from CPC with the RONI data.

 https://x.com/NWSCPC/status/2021947407643406449



https://www.cpc.ncep.noaa.gov/products/ ... disc.shtml

In summary, a transition from La Niña to ENSO-neutral is expected in February-April 2026 (60% chance), with ENSO-neutral likely persisting through the Northern Hemisphere summer (56% chance in June-August 2026)

https://i.imgur.com/7Uw6RxM.png

So you're telling me that this update now includes the RONI data?

[mixedDanilo.E]

On another note, Latest hovmollers from the GFS indicate strong trade bursts til the end of the month...

[cycloneye]

Breaking News

Big update and change from CPC with the RONI data.

 https://x.com/NWSCPC/status/2021947407643406449



https://www.cpc.ncep.noaa.gov/products/ ... disc.shtml

In summary, a transition from La Niña to ENSO-neutral is expected in February-April 2026 (60% chance), with ENSO-neutral likely persisting through the Northern Hemisphere summer (56% chance in June-August 2026)

https://i.imgur.com/7Uw6RxM.png

So you're telling me that this update now includes the RONI data?

That is right.

[869MB]

Still the january data has not come out in this site.

https://oceanview.pfeg.noaa.gov/erddap/ ... e?time,PDO

Interesting stuff, because NOAA has clearly has updated their PDO chart with the -1.19 value for January 2026. https://www.ncei.noaa.gov/access/monitoring/pdo/

Random observation but I never realize how low the index got last summer, it tanked to -4.21 in July! (lowest on record)

Oh yeah last month I posted on the Texas Thread how you have to go back to September 2019 to find a month when the PDO was greater than 0.00. And 2015 was the last calendar year where every month’s value was greater than 0.00 from January to December.

[cycloneye]

Question to the members. Is there a possible scenario depending on how strong it gets that the upcoming El Niño will be long in duration around 2 to 3 years? 26-27-28?

[Dean_175]

Question to the members. Is there a possible scenario depending on how strong it gets that the upcoming El Niño will be long in duration around 2 to 3 years? 26-27-28?

Unlikely. Of the recent multi-year Ninos, it was either a weak event or something was off with the normal timing of coupling between atmosphere and ocean. For example, 1986 onset very late in the calendar year. This delayed negative feedback and the event had an unusual secondary peak the following summer. 2014 was weak and didn’t show significant coupling until 2015. 2018/2019 was weak and not very robust. There is nothing abnormal so far that would make me think of a multi-year Nino. I think we would need to see this one become stunted but without significant deterioration of the warm pool.

La Niña is more likely to recur than El Niño. That is one asymmetry in ENSO. La Niña commonly repeats, while El Niño rarely does. El Niño seems to have higher max potential amplitude instead.