Chances of El Niño are expected to increase after May 2026, with forecasts indicating the event could strengthen through the summer and reach peak intensity later in the year, typically between October and February.
If the pattern develops as projected, it may influence weather conditions in regions such as California, particularly during the winter months.
Global forecasting systems suggest El Niño is likely to form and intensify through 2026. Projections from the European Centre for Medium-Range Weather Forecasts (ECMWF) and the Copernicus Programme indicate a faster warming trend in some model scenarios.
In contrast, predictions from the International Research Institute for Climate and Society (IRI) and the National Oceanic and Atmospheric Administration (NOAA) suggest a slower transition from neutral conditions, with a more gradual buildup in the months ahead.
El Niño Forecasts
The March model forecasts showed a transition away from La Niña toward neutral conditions, with warming expected to develop later in the year.
However, the April forecast shows that the ocean temperature irregularities had already reached around +0.5°C, a level commonly associated with the early stages of El Niño. This suggests that warming in the Pacific Ocean has already started.
European model forecasts indicate a rapid rise in temperature anomalies starting in spring, when values are expected to reach around +1°C to +1.5°C by May and June. The temperatures would then climb between +2°C and +3°C from July to September. Such levels suggest that the event is in the moderate to strong category, with the possibility of becoming strong.
Moreover, a recent burst of westerly winds over the Pacific is helping push warm water eastward, which has been a key step in the development of El Niño.
Give that development, warming in the ocean is likely to speed up. Some scientists say it increases the chances of a stronger event. Paul Roundy, an atmospheric scientist at the University at Albany, said the current setup has “real potential for the strongest El Niño event in 140 years.”
Real potential for the strongest El Niño event in 140 years. https://t.co/aT9IdIg4Fn
— Paul Roundy (@PaulRoundy1) April 5, 2026
Even then, forecasters maintain that it is too early to say how strong it will become, and the most extreme outcomes remain uncertain.
Projections from the IRI and NOAA describe a slower transition. Normal conditions are expected to stay through the spring months, delaying the clear emergence of El Niño until the June to August period. These models also note the uncertainty about the strength of the event, with probabilities increasing over time rather than indicating an immediate shift.
Potential Impact in California
The potential impact on California mainly depends on how strong the event becomes. A strong El Niño is generally associated with a higher likelihood of wetter conditions, particularly during the winter months.
However, weaker or moderate events tend to produce less predictable outcomes, with no consistent pattern across all regions. The expected peak around October could shape weather patterns during the winter of 2026-27.
What is El Niño?
El Niño is a climate pattern that is defined by unusually warm ocean temperatures in the central and eastern Pacific. It is part of the El Niño-Southern Oscillation, which includes both warming and cooling phases. These shifts influence weather patterns across the globe, affecting rainfall, temperatures, and storm activity.
The phenomenon does not follow a fixed schedule but generally occurs every two to seven years. Events usually last between nine and 12 months, although some can persist for longer periods. Its development is linked to changes in ocean and atmospheric conditions across the Pacific.
Under normal conditions, trade winds push warm surface water toward the western Pacific, causing colder, nutrient-rich water to rise near South America through upwelling. During El Niño, these winds weaken, allowing warm water to shift eastward. This reduces upwelling and results in a buildup of heat at the ocean surface.
The current marine heat wave is a probable explanation for the excessive bird deaths we’re seeing.
Search “news marine heat wave southern california birds”
from 2020:
https://www.nps.gov/articles/blametheblob.htm
2019:
https://www.nps.gov/articles/five-years-after-blob-another-marine-heatwave.htm
Current news report from CBS San Diego:
https://www.youtube.com/watch?v=bixoM6wmHzI
“For more than a century, shoreline stations operated by the Scripps Institution of Oceanography have measured water temperatures along the California coast. This year, they are flashing a warning sign.
Over the last three months, several stations have repeatedly posted record-breaking daily high temperatures – with the La Jolla station registering temperatures a full 10F above historical average at one point last month.
The waters of southern California historically warm every few years as tropical currents make their way north, a phenomenon known as El Niño. But the marine heatwave that started last fall wasn’t caused by tropical currents. Instead, a high-pressure atmospheric system – think of calm, sunny days – has perched above southern California, warming both air and sea above historic levels. The same phenomenon has helped fuel a ferocious California heatwave on land.”
Article continues at:
https://www.theguardian.com/us-news/2026/apr/04/high-ocean-temperatures-california-marine-heatwave