bluewave

There aren’t really any inverse temperature correlations between October and the winter. When relationships do exist, it’s more on a CONUS and North American level of similar October to winter temperatures. For instance very warm Octobers across the CONUS and North America sometimes continue into the winter. Same for very cold Octobers continuing into the winter. Our last much weaker super El Niño in 2023 -2024 had a very warm October in the Northeast and this continued for the winter. Other times the October pattern doesn’t continue into the winter. So it’s mostly magnitude dependent across a larger area.

All-time records continue to increase. This was the first +5.3 week ever for Nino 1+2 ONI. Nino 3 and 3.4 records are also being set. Highlighting 1+2 due to how low the models have been here. While the Euro is much better than the CFS, they both missed how east based this has become. The interesting thing about both models is that they start to show a second rise in Nino 1+2 heading into next spring on the Euro and early summer on the CFS. The Euro October update was just issued. Nino 3 staying above +4 into February would also be a first . The previous Nino 3 February record was +2.8 in 1998. So it’s possible that the +30C warm pool makes it as far east as Nino 3 for the first time. https://www.cpc.ncep.noaa.gov/data/indices/ 30SEP2026 26.1 5.3 29.0 4.0 29.9 3.2 29.9 1.2 04FEB1998 28.0 2.4 28.9 2.8 28.9 2.3 28.8 0.7

Last month was N to a little AN for most stations with the exception of the immediate Long Island Sound stations like BDR and LGA. All the other months back to March were also some degree of AN. With such extensive ridging and record CONUS warmth, there wasn’t much cooler air around. So the few cooler spots last month like LGA and BDR had to rely on lower daytime highs rather than cooler minimums. May managed to finish a little above even with the cooler conditions just to our West. The record warm day where parts of the area reached 100° for the first time in May put that month over the top. So the theme has been back and forth with the warmer departures being more impressive than the cooler ones. October looks like a continuation of the same theme. Very warm start to the month with a cool down this week. But we warm right back up into the 70s again. Whether we reach 80° again by mid-October will be contingent on sky conditions, wind direction, and how far north the moisture near the Gulf gets.

No need to search very far since it has been the dominant pattern since March.

Models shifting to a much stronger Southeast ridge in around a week. So we could continue the drier pattern. More 80° days would be possible with enough sun and SW flow. New run Old run

You would have loved the 1960s with snowy winters and drought conditions the rest of the year. Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean T 0.4 8.3 7.1 10.1 6.1 0.1 32.0 1959-1960 0.0 0.5 15.8 2.5 1.9 18.5 0.0 39.2 1960-1961 T 0.0 18.6 16.7 18.2 1.2 T 54.7 1961-1962 0.0 T 7.7 0.6 9.6 0.2 T 18.1 1962-1963 T T 4.5 5.3 3.7 2.8 T 16.3 1963-1964 0.0 T 11.3 13.3 14.1 6.0 T 44.7 1964-1965 0.0 0.0 3.1 14.8 2.5 2.8 1.2 24.4 1965-1966 T 0.0 T 11.6 9.8 T 0.0 21.4 1966-1967 0.0 0.0 9.1 1.4 23.6 17.4 T 51.5 1967-1968 0.0 3.2 5.5 3.6 1.1 6.1 0.0 19.5 1968-1969 0.0 T 7.0 1.0 16.6 5.6 0.0 30.2

Subsurface warmth continuing to increase. Getting close to +12 now in spots. The +30C warm pool shifting further east is also a first.

JMA has a great site with many different ENSO composites. https://ds.data.jma.go.jp/tcc/tcc/products/clisys/enso_statistics/index.html

October is showing overlapping influences compared to past El Nino climatology. The typical -EPO blocking ridge is displaced further south than usual into the Western US. This is a continuing theme from last spring with enhanced mid-latitude ridges. It’s developing a little more south of 2015 which would be the closest match. The North Pacific low looks displaced or stretched into a +WPO position.

Unfortunately, the arrival of spring warmth is coming earlier while the date of the last freeze has held more steady over time.

The Euro was fairly close this month. It had forecast a global mean average temperature of 1.67 C in September. The September average came in a +1.63 C.

The original paper that RONI is based on discusses it mostly being developed to prevent weak La Nina’s from getting lost in the mix rather than some deficiency in measuring super El Niño events. Plus the weaker El Niños not being able to fully couple. Both instances were also a function of the record WPAC warm pool. So the ONI and the absolute SSTs are a good measure of how intense this event is becoming. My original ONI post was correct as the original ONIs we relied on for many years into the 2010s had the ONI with the 1972-1973 event peaking at the +2.0 to +2.1 range. So a lower end super El Niño event.

The planet doesn’t care about squabbles based on how humans define things. It just responds to the actual temperatures. So the headline story for the planet right now is that we are exceeding past super El Niño events by a wide margin and it’s still only early October. All-time SST records are increasing from Nino 3.4 to 1.2.

The old ONI that we used before the recent updates was also +2.1. It’s perfectly fine to use the ONI as a measurement of the actual intensity of the event. With an event as extreme as this RONI can make the event seem weaker than it actually is. https://x.com/BenNollWeather/status/2105084471750037987 From a scientific perspective, part of the challenge is that weather patterns in different parts of the world are not equally sensitive to the same El Niño index. In South America, for example, Niño 1+2 is particularly important, while patterns across the U.S., Australia, Singapore and many other regions are more closely associated with conditions in Niño 3.4. Some rely on a blend of ocean-atmosphere indicators (e.g., ONI, RONI, SOI, EQSOI, OLR, MEI, etc.) to capture coupling. For the public, the minutiae of those indices matter much less. What's record-breaking in one index may not be record-breaking in another, and I think it's incumbent on the communicator to make that clear. At the very least, if a record is being claimed, then a reference to the index/data set being used is essential (see attached). Not everyone will read the fine print, but it's duty of care. I think there's an opportunity for a larger body to step in (e.g., WMO) to classify a record El Niño event, if there's sufficient evidence, like they would a global temperature record. Lastly, I think the RONI-ONI debate will go on for years. RONI is more closely tied to atmospheric responses. ONI informs absolute extremes. In the ONI space, every tenth of a degree matters to global water vapor levels and temperatures, and therefore, the weather. The best approach is up for debate, but I think showing both is a fair balance. One El Niño, many ways to measure it! https://x.com/WeatherProf/status/2105064342441939064 On the other hand, if you are trying to communicate the absolute strength of this El Niño vs other historic El Nino’s, how global warming has impacted it, or how it may impact global temperatures in the coming months - then use the traditional ONI or raw sea surface temperature anomalies. Certainly it can be confusing to the public, but I’d argue the relative index inadvertently obscures the larger climate signal - it can be misleading because it basically subtracts the warming that has occurred in recent decades. So it’s unintentionally deceptive.

Warm spots from Philly to Newark could be closer to the AI in the mid to upper 80s with enough sun today. It’s possible some of the locally cooler spots across the region could dip under 40° next week with some frost. But looks like a quick warm up a few days later. Not much cold to work with so much warmth across the CONUS.