NOAA forecasts a greater than 90% chance of a very strong El Niño late this year, with a 69% chance of reaching historic +2.5°C levels between October and December.
New computer models suggest that sea surface temperatures could exceed records going back to 1950.
Warm water building up near the equator causes a change in air pressure, which would push the Pacific jet stream south. Americans may need to prepare for redirected storm tracks in fall and winter.
How ocean warming is tracked across the Pacific Ocean
The National Oceanic and Atmospheric Administration (NOAA) is a U.S. federal scientific agency with the important mandate of climate tracking and forecasting.
Data from buoys and satellites measuring sea surface temperatures shows that they are rising well above average for this time of the year. Weak trade winds mean that normal levels of upwelling of cold water off South America. This has facilitated faster spreading of heat east on the ocean surface.
Subsurface sensors indicate that a substantial layer of warm water is trapped along the equator, supplying steady energy to the atmosphere.
Near the International Date Line, cloud cover shows that air currents are already reacting to the warm water below.
Present conditions are measured by the physical readings, but models have to be used for future projections. The warming phase we are experiencing right now has been verified, but the ultimate strength of the upcoming El Niño system depends on whether trade winds stay weak over the remainder of the summer or not.
Modeling, projections, and probability
Climate models project seasonal trends using atmospheric and ocean data. NOAA now projects a greater than 90% chance of a very strong El Niño this fall and winter, with a 69% probability of hitting historic +2.5°C RONI levels from October to December 2026.
The computer simulations work by comparing current levels of heat accumulation with major past events, such as the El Niños of 1997 and 2015. NOAA’s latest climate forecast gives a 70% chance that ocean temperatures will rise at least 2.0°C above average this winter, combining insights from multiple dynamic models, such as the NOAA Coral Reef Watch, and real-time observations.
This is by no means a guaranteed outcome; rather, this is a computer-generated consensus backed up by decades of historical climate data. Real-world atmospheric conditions can still change weather behavior even if the models consistently point to high levels of warming.
High winds in the tropical regions or a shift in the air above the polar regions could still weaken ocean-air conditions. This would keep peak temperatures below model forecasts as fall weather reaches North America.
How ocean heat shifts North American weather patterns
The physics connecting tropical water to North American weather comes down to atmospheric teleconnections.
As tropical Pacific waters heat up, deep thunderstorm activity shifts east toward the International Date Line. This heat release changes air pressure patterns high in the atmosphere, pushing the Pacific jet stream south and stretching it across the southern United States.
Historical weather records confirm that a southern jet stream directs winter storms straight into California and the Gulf Coast, according to the Climate Prediction Center. At the same time, it leaves the Pacific Northwest and northern plains unusually warm and dry.
The model is a forecast, not a certainty
Scientists caution that while jet stream shifts are an established response to ocean warming, specific regional impacts remain forecasts rather than certainties. Local weather can still diverge from seasonal trends due to short-term atmospheric variability.
As buoy networks log equatorial heat, climatologists are monitoring air currents to confirm whether model projections turn into reality.
Tracking ocean temperatures shows how tropical waters influence global weather, while marking the limits of seasonal forecasting. Computer models can map out jet stream shifts months in advance, but local winter conditions across North America will still depend on daily atmospheric shifts.
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