2026-2027 Super El Nino

[so_whats_happening]

So when can we start to discuss the differences between how these two similiarish ENSO events will evolve?

 

[donsutherland1]

3 hours ago, snowman19 said:

@bluewave @donsutherland1 @forkyfork @LakePaste25 The projected median (peak) of +3.0C RONI come November would be an all-time record on that index. The projected median (peak) of +3.4C traditional ONI, also come November, would be an all-time record as well
 

It will be interesting to see how strong the ongoing and rapidly developing El Niño becomes. Only the 1997-98, 2015-16, and 2023-24 El Niño events saw the 6-week moving average for Region 3.4 reach or exceed +0.9°C in June or July. 

[Typhoon Tip]

As the humanity bus goes over the cliff…

[GaWx]

42 minutes ago, so_whats_happening said:

So when can we start to discuss the differences between how these two similiarish ENSO events will evolve?

 

 Thanks. Some of us have already been discussing ‘26-7 vs ‘97-8. On Saturday I posted that per the Euro progs, ‘26-7 is looking to evolve into a much less E based Nino than ‘97-8, which became the most E based Nino on record (back to 1951-2). When I refer to E based, I’m referring to the differences between 1+2 and 3 vs 3.4 and 4. This is what I posted:

 

More on 97. Here were the monthlies:

                     1+2       3          4  

    3.4
1997   6   26.12    3.00   28.13    1.51   29.23    0.26   28.82    1.09
1997   7   25.59    3.63   27.90    2.09   29.37    0.47   28.86    1.56
1997   8   24.96    3.96   27.71    2.59   29.29    0.50   28.75    1.89
1997   9   24.69    3.96   27.74    2.84   29.44    0.68   28.85    2.13
1997  10   24.69    3.67   28.06    3.08   29.34    0.58   29.08    2.36
1997  11   26.12    4.47   28.37    3.27   29.39    0.69   29.12    2.41
1997  12   27.06    4.25   28.53    3.30   29.11    0.57   28.89    2.29
1998   1   28.12    3.55   28.74    3.08   28.95    0.64   28.93    2.38
1998   2   28.74    2.64   28.90    2.49   28.79    0.59   28.78    2.03

 1+2 (peak 4.47) and 3 (peak 3.3) were way, way stronger than 4, which remained just wk (peak 0.69) and even way stronger than 3.4 (peak 2.41)!

 The forecast for ‘26 is much stronger in 3.4/4 and stronger in 3, but not as strong in 1+2:

Per latest Euro, here are peak non-rel. monthlies:

1+2: 3.9

3:    3.9

3.4: 3.7

4:    2.4

 That’s only a contrast of 1.5 from E to W compared to 3.8 in ‘97! And contrast from 1+2 to 3.4 is a mere 0.2 vs 2.1 in ‘97!! So, the prog is for ‘26 to be E based but way more balanced and thus not nearly as E based as the extremely E based ‘97.

 

[so_whats_happening]

11 minutes ago, GaWx said:

 Thanks. Some of us have already been discussing ‘26-7 vs ‘97-8. On Saturday I posted that per the Euro progs, ‘26-7 is looking to evolve into a much less E based Nino than ‘97-8, which became the most E based Nino on record (back to 1951-2). When I refer to E based, I’m referring to the differences between 1+2 and 3 vs 3.4 and 4. This is what I posted:

 

More on 97. Here were the monthlies:

                     1+2       3          4  

    3.4
1997   6   26.12    3.00   28.13    1.51   29.23    0.26   28.82    1.09
1997   7   25.59    3.63   27.90    2.09   29.37    0.47   28.86    1.56
1997   8   24.96    3.96   27.71    2.59   29.29    0.50   28.75    1.89
1997   9   24.69    3.96   27.74    2.84   29.44    0.68   28.85    2.13
1997  10   24.69    3.67   28.06    3.08   29.34    0.58   29.08    2.36
1997  11   26.12    4.47   28.37    3.27   29.39    0.69   29.12    2.41
1997  12   27.06    4.25   28.53    3.30   29.11    0.57   28.89    2.29
1998   1   28.12    3.55   28.74    3.08   28.95    0.64   28.93    2.38
1998   2   28.74    2.64   28.90    2.49   28.79    0.59   28.78    2.03

 1+2 (peak 4.47) and 3 (peak 3.3) were way, way stronger than 4, which remained just wk (peak 0.69) and even way stronger than 3.4 (peak 2.41)!

 The forecast for ‘26 is much stronger in 3.4/4 and stronger in 3, but not as strong in 1+2:

Per latest Euro, here are peak non-rel. monthlies:

1+2: 3.9

3:    3.9

3.4: 3.7

4:    2.4

 That’s only a contrast of 1.5 from E to W compared to 3.8 in ‘97! And contrast from 1+2 to 3.4 is a mere 0.2 vs 2.1 in ‘97!! So, the prog is for ‘26 to be E based but way more balanced and thus not nearly as E based as the extremely E based ‘97.

 

A lot of this gets lost in the miasma of whatever happens in this thread. Thanks and I agree while records could be set if things set up perfectly that contrast west to east is important in overall effects we will see in the CONUS. We have not been able to get the contrast of warm east cool west of the tropical Pacific for awhile. I would like to think a quicker onset of the Nino might play a role in the winter outcome as well.

[Maestrobjwa]

Anybody got any data pn how often super niños spawn double-dip la ninas?

[Stormchaserchuck1]

14 minutes ago, Maestrobjwa said:

Anybody got any data pn how often super niños spawn double-dip la ninas?

Good question. I was going to ask if anyone wants to discuss the snap-back tendency that the historical Strong Nino analog has given us, but I think a lot of attention is on this event because it may end up extreme. I think the Nina snap-back won't be as strong this go around, but it's early. Something to watch is if cold water starts to get going in the western and central subsurface, through the next few months and into the Fall and Winter. The big, long lasting Nina's all had major cold in the subsurface during the height of previous Strong Nino peak. 

Here is the historical dataset: Climate Prediction Center - Relative Oceanic Niño Index (RONI)

72-73, 82-83, 97-98, 15-16, and 23-24 are your Super Nino's. 

Subsurface data since 1979 can be found here: Data Display and Delivery | Global Tropical Moored Buoy Array 20c Isotherm depth is probably the easiest variable to hone in on. 

[GaWx]

31 minutes ago, Maestrobjwa said:

Anybody got any data pn how often super niños spawn double-dip la ninas?

1877-8 followed by cold neutral and then weak La Nina

1888-9 followed by strong La Niña and then weak La Niña

But in neither of these cases were they immediately preceded by La Niña like ‘26.

[snowman19]

[GaWx]

55 minutes ago, snowman19 said:

 

Note that Nino 3 anomalies are stronger than Nino 1+2. So, this prog isn’t severely E based as of 2/1/27.

[snowman19]

Note that Nino 3 anomalies are stronger than Nino 1+2. So, this prog isn’t severely E based as of 2/1/27.

 
 

 
 

The new DWKW has already started:

 
And wow! 3 TC’s have formed in less than a week in the EPAC. Historic TC season coming up there

 

[bluewave]

19 hours ago, GaWx said:

Thanks, Chris

-Long range model winter forecasts have, indeed, tended to be too cold on average based on my recollection although the Euro has missed on both sides. So, I wouldn’t be shocked if 25-6 also comes in warmer than today’s forecast, but that remains to be seen.

-But keep in mind that you essentially are showing a super Nino sample size of just one (2015-6 done in August) since 2023-4 wasn’t a true super (RONI peaked at only +1.49). ONI had ~0.5C excess due to very warm surrounding tropical waters from GW inflating the ONI.

-Also, other super Ninos had a fairly similar temp. pattern to what the NMME shows overall.

Ultimately El Niños are ranked by their jump in global temperatures. 2023-2024 had a larger rise in global temperatures than previous super El Niño events. So relying on the RONI metric is inadequate to describe these much stronger events.

Even the authors of the paper which RONI is based on said the scale may need to be reevaluated in the future. So I view it as an experimental index which should be used alongside the traditional ONI scale.

It can be used for assessing features like El Niño rainfall and the strength of the Aleutian Low. But ONI was closer to reality on temperatures during 2023-2024 than RONI. Plus the 500 mb ridge over North America was more in line with ONI. 

2023-2024 was the warmest winter on record for the CONUS which none of the models beyond 15 days forecast. The warmth across the Northern Tier even exceed some of the previous super El Niño events.

Seasonal models don’t have the ability to see extremes. Extreme warmth has been greatly exceeding extreme cold. So the long range models miss extreme warmth much more often since extreme cold has become so rare.

About the only thing I use the seasonal models for are the Nino plumes once we get past the spring predictability barrier in early June. But we knew something really big was coming months ago with the record WWBs and kelvin waves.

https://journals.ametsoc.org/view/journals/clim/37/4/JCLI-D-23-0406.1.xml

As they previously cautioned, in the future, if there are significant divergences between the tropical mean state and trends in the Niño indices, then this index will need to be re-evaluated. We hope this work motivates additional studies and simulations of these indices in a changing climate.

[GaWx]

2 hours ago, bluewave said:

Ultimately El Niños are ranked by their jump in global temperatures. 2023-2024 had a larger rise in global temperatures than previous super El Niño events. So relying on the RONI metric is inadequate to describe these much stronger events.

Even the authors of the paper which RONI is based on said the scale may need to be reevaluated in the future. So I view it as an experimental index which should be used alongside the traditional ONI scale.

It can be used for assessing features like El Niño rainfall and the strength of the Aleutian Low. But ONI was closer to reality on temperatures during 2023-2024 than RONI. Plus the 500 mb ridge over North America was more in line with ONI. 

2023-2024 was the warmest winter on record for the CONUS which none of the models beyond 15 days forecast. The warmth across the Northern Tier even exceed some of the previous super El Niño events.

Seasonal models don’t have the ability to see extremes. Extreme warmth has been greatly exceeding extreme cold. So the long range models miss extreme warmth much more often since extreme cold has become so rare.

About the only thing I use the seasonal models for are the Nino plumes once we get past the spring predictability barrier in early June. But we knew something really big was coming months ago with the record WWBs and kelvin waves.

https://journals.ametsoc.org/view/journals/clim/37/4/JCLI-D-23-0406.1.xml

As they previously cautioned, in the future, if there are significant divergences between the tropical mean state and trends in the Niño indices, then this index will need to be re-evaluated. We hope this work motivates additional studies and simulations of these indices in a changing climate.

Thanks, Chris. The following two sources are very recent (2026) and are in support of RONI over ONI:

New NOAA El Niño-Southern Oscillation Index Supports Drought Early Warning

RONI accounts for the long-term ocean temperature trends in a way that the traditional ONI does not, thus providing a better representation of the seasonal climate variability.

Not accounting for the warming oceans means recent El Niño temperature anomalies look bigger than they really are, and La Niña anomalies look smaller.

Consider the last six winters: Five of the last six winters saw a La Niña pattern, which is one of the reasons much of the southern half of the Nation experienced  persistent and recurring drought throughout the first half of this decade. Using the traditional ONI, 2020-2023 experienced a “triple-dip” La Niña, but RONI classified this as one continuous, unbroken La Niña event that lasted three years. These years were also very dry across the Southwest and Southern Plains.

The 2024-2025 and 2025-2026 winters were ENSO-neutral using the traditional ONI. Using RONI, these events would instead be classified as definitive La Niñas. 
 
 Winter 2025-2026 brought Moderate to Severe Drought (D1-D2) or worse for a broad swath of the Southern U.S. from Arizona to Florida. The La Niña pattern in place since around August 2025 is a primary driver of this drought. This season mostly followed the traditional La Niña response, with a few exceptions

https://www.drought.gov/news/new-noaa-el-nino-southern-oscillation-index-supports-drought-early-warning-2026-03-11

————————————————

Relative Oceanic Niño Index (RONI)

A clearer, more reliable way to track El Niño and La Niña

More reliable in real-time: ONI depends heavily on the choice of a 30‑year average. As tropical ocean temperatures shift over time, that reference can lag behind current conditions. RONI reduces this sensitivity, leading to more consistent classifications. 
 

More stable ENSO classifications

 RONI is less sensitive to which 30‑year reference period is used, meaning that the classification of past El Niño, Neutral, and La Niña events is more stable.

 

Clearer connection to impacts

RONI better reflects when ENSO‑related atmospheric patterns are actually present, improving alignment with seasonal temperature and precipitation outlooks.

How is this change to RONI going to benefit decision makers who rely on an accurate ENSO forecast?

 RONI is better able to capture the expected changes in the atmosphere inherent to ENSO, and El Niño/La Niña categorization is more stable even as the climatology changes. Because RONI is more accurately reflecting the ENSO state, users will be able to more accurately make decisions that rely on associated seasonal forecasts and risk assessments.

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/pdf/roni-info-may-2026.pdf

 

 

[bluewave]

35 minutes ago, GaWx said:

Thanks, Chris. The following two sources are very recent (2026) and are in support of RONI over ONI:

New NOAA El Niño-Southern Oscillation Index Supports Drought Early Warning

RONI accounts for the long-term ocean temperature trends in a way that the traditional ONI does not, thus providing a better representation of the seasonal climate variability.

Not accounting for the warming oceans means recent El Niño temperature anomalies look bigger than they really are, and La Niña anomalies look smaller.

Consider the last six winters: Five of the last six winters saw a La Niña pattern, which is one of the reasons much of the southern half of the Nation experienced  persistent and recurring drought throughout the first half of this decade. Using the traditional ONI, 2020-2023 experienced a “triple-dip” La Niña, but RONI classified this as one continuous, unbroken La Niña event that lasted three years. These years were also very dry across the Southwest and Southern Plains.

The 2024-2025 and 2025-2026 winters were ENSO-neutral using the traditional ONI. Using RONI, these events would instead be classified as definitive La Niñas. 
 
 Winter 2025-2026 brought Moderate to Severe Drought (D1-D2) or worse for a broad swath of the Southern U.S. from Arizona to Florida. The La Niña pattern in place since around August 2025 is a primary driver of this drought. This season mostly followed the traditional La Niña response, with a few exceptions

https://www.drought.gov/news/new-noaa-el-nino-southern-oscillation-index-supports-drought-early-warning-2026-03-11

————————————————

Relative Oceanic Niño Index (RONI)

A clearer, more reliable way to track El Niño and La Niña

More reliable in real-time: ONI depends heavily on the choice of a 30‑year average. As tropical ocean temperatures shift over time, that reference can lag behind current conditions. RONI reduces this sensitivity, leading to more consistent classifications. 
 

More stable ENSO classifications

 RONI is less sensitive to which 30‑year reference period is used, meaning that the classification of past El Niño, Neutral, and La Niña events is more stable.

 

Clearer connection to impacts

RONI better reflects when ENSO‑related atmospheric patterns are actually present, improving alignment with seasonal temperature and precipitation outlooks.

How is this change to RONI going to benefit decision makers who rely on an accurate ENSO forecast?

 RONI is better able to capture the expected changes in the atmosphere inherent to ENSO, and El Niño/La Niña categorization is more stable even as the climatology changes. Because RONI is more accurately reflecting the ENSO state, users will be able to more accurately make decisions that rely on associated seasonal forecasts and risk assessments.

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/pdf/roni-info-may-2026.pdf

 

 

It’s a bit like relying on temperature departures rather than absolute rankings in a warming climate. But the global temperatures will respond to the absolute Nino 3.4 SSTs rather than the departures which update to reflect the warming baseline each decade. 

The value of RONI is probably more for La Ninas where the WPAC warm pool has been defining La Nina’s more than the Nino region cold pool of the past.

But the absolute strength of La Niña measured through Nino 3.4 SSTs has been shrinking  since we haven’t had a strong La Niña by actual SSTs since 2010-2011.

[LakePaste25]

There’s different uses for both. If you’re comparing the Nino 3.4 to historical rankings or you want to see how much heat is being released into the atmosphere then yes, the absolute ONI should be used. But if you’re trying to measure a sensible mid latitude response then you would use RONI. 

[bluewave]

19 minutes ago, LakePaste25 said:

There’s different uses for both. If you’re comparing the Nino 3.4 to historical rankings or you want to see how much heat is being released into the atmosphere then yes, the absolute ONI should be used. But if you’re trying to measure a sensible mid latitude response then you would use RONI. 

I agree with most of what you just said. But I have a partial disagreement with you on what constitutes a sensible mid latitude response. The response has two components.

The first is the strength of the 500mb ridge across Canada and the Northern Tier of the CONUS. During the 2023-2024 super El Niño this ridge was more expansive than the 1997-1998 super El Niño pressing further south toward the mid-Atlantic and enhancing the warmth.

So this wasn’t reflected in the RONI only peaking at 1.5. But the RONI was more representative of the weaker Aleutian low and Mid-Atlantic to Southeast low.

We can also see the RONI inconsistency with the 2015-2016 super El Niño in another way. While it was better matched with the ONI than 2023-2024, the Aleutian low was still much weaker than 1997-1998. Plus the rainfall response was much less in places like CA along with more of a ridge in the Eastern CONUS than past super El Niños.

[LakePaste25]

3 minutes ago, bluewave said:

I agree with most of what you just said. But I have a partial disagreement with you on what constitutes a sensible mid latitude response. The response has two components.

The first is the strength of the 500mb ridge across Canada and the Northern Tier of the CONUS. During the 2023-2024 super El Niño this ridge was more expansive than the 1997-1998 super El Niño pressing further south toward the mid-Atlantic and enhancing the warmth.

So this wasn’t reflected in the RONI only peaking at 1.5. But the RONI was more representative of the weaker Aleutian low and Mid-Atlantic to Southeast low.

We can also see the RONI inconsistency with the 2015-2016 super El Niño in another way. While it was better matched with the ONI than 2023-2024, the Aleutian low was still much weaker than 1997-1998. Plus the rainfall response was much less in places like CA along with more of a ridge in the Eastern CONUS than past super El Niños.

I mean aren’t mid latitude ridges expanding due to global warming regardless? The SE ridge is also getting stronger and more expansive despite La Nina’s being weaker on the absolute ONI scale…so I do not know if this is exclusive to RONI vs ONI.