Most readers are probably well aware that El Niño is on the way for next winter; the forecasts have been well-publicized. Normally one would be wise to take El Niño forecasts with a grain of salt at this time of year, because there is a notorious "spring barrier" of predictability in Northern Hemisphere spring, but in this case the signals are so strong and coherent that there's little doubt of the outcome.
The most compelling evidence that a major El Niño is about to emerge can be seen in the profile of subsurface temperature anomalies in the equatorial Pacific. The figure below is a couple of weeks out of date, but it shows a very intense warm anomaly below the surface, and this is migrating eastward and upward. As the warmth continues to emerge at the surface, East Pacific equatorial surface water temperatures will become much warmer than normal, consistent with a strong El Niño signature.
The warmth produced by the subsurface anomaly will add to the substantial surface warming that has already occurred in the last few months, so it seems inevitable that the equatorial SST anomalies are going to become quite extreme in the next few months. The canonical Niño3.4 SST index is already near 1°C above normal, although this includes a contribution of about 0.5°C from long-term warming in recent decades:
Here's a chart showing the recent progression of Niño3.4 SST anomaly forecasts from ECMWF's seasonal model. The red line is the latest forecast; the model has been adjusting warmer with every run in recent months.
If the forecast is correct, the Niño3.4 anomaly may approach +3°C by autumn, with the modern record being +2.7°C in November 2015 (relative to a 1991-2020 baseline).
What does this mean for Alaska? We'll discuss prospects for next winter another time, but for summer the history of past years with strong El Niño conditions (see below) suggests a heightened probability of above-normal temperatures, driven by relatively high pressure (ridging) from Alaska to the Canadian Arctic. The top analog years also show dry summer conditions in Southeast Alaska and hints of dryness in southern interior and western Alaska. Note that this is based simply on the 10 years since 1950 with the most positive Multivariate ENSO Index in June through August.
However, not all El Niños are created equal, and analog years show a lot of variability. To illustrate this, here are temperature percentile maps for six summers when a robust El Niño developed by autumn following La Niña-like conditions the previous winter. Where possible, I've used a preceding 30-year baseline for a fair comparison across the decades.
More recently, 2015 produced a very strong El Niño, but that episode didn't emerge from a cool phase in the previous winter. There was also a robust El Niño in 2023, although its oceanic warm signature was inflated by unusual global warmth.
Not surprisingly, temperatures from the northern Gulf Coast to southwestern Alaska tend to be linked to the PDO phase, which was positive in 1957, 1986, (especially) 1997, and 2015, but negative in 1965, 1972, and 2023. Elsewhere, variability is large among the analog years, although there isn't much cool to be found in northern and western - or southeastern - Alaska.
Similar maps for precipitation are included below.
It's difficult to pick out any consistent moisture signals on the maps, but interestingly ground-truth data from Fairbanks shows that none of the top 6 El Niño analog years had above-normal rainfall for May through September. Click the figure below to enlarge (2014 is included only to show the record wettest summer):
Juneau also shows distinct indications of a (relatively) dry summer when El Niño develops in a similar way:
Summer rainfall can go either way in Anchorage, however:
For a more comprehensive look at all the seasonal climate guidance for this summer, I highly recommend tuning in to Rick Thoman's briefing on May 22:
https://uaf-accap.org/event/may2026-climate-outlook/
