The Climate Prediction Center issued its latest ENSO Diagnostic Discussion on February 12, 2026, confirming that La Niña is fading and that ENSO-neutral conditions are favored to persist through Northern Hemisphere summer 2026. That shift carries direct consequences for the March-through-May seasonal outlook across the United States, where earlier forecasts had been built around La Niña patterns of a wet Northwest and dry Southwest. With the next round of official seasonal outlooks scheduled for February 19, 2026, covering the spring period and beyond, forecasters, farmers, and water managers face a narrowing window to adjust plans as the ocean signal that anchored winter predictions loses its grip.
La Niña Losing Steam Beneath the Surface
The physical evidence for La Niña’s decline is stacking up fast. The CPC’s 30-day outlook discussion, issued January 31, 2026, reported that Nino-3.4 waters are warming and that equatorial upper-ocean heat anomalies have reached their most positive value in at least a year. That subsurface heat buildup is significant because it acts as a leading indicator: warm water pooling beneath the surface tends to erode the cool-surface signature that defines La Niña, often weeks before the change shows up in standard monitoring indices.
The same discussion placed the probability of a transition to ENSO-neutral at 75 percent, a strong consensus signal that the event is running out of energy. Separately, analysts at Climate.gov noted that La Niña is likely gone by the end of April, with fading conditions already reducing forecasters’ confidence in what the rest of spring and summer will look like. That erosion of confidence is the core problem: once the dominant ocean-atmosphere driver weakens, seasonal outlooks lose their sharpest predictive edge, and the range of plausible outcomes widens for sectors that depend on early guidance.
January Outlooks Built on a Pattern That May Not Last
The CPC’s prognostic discussion for long-lead seasonal outlooks, issued January 15, 2026, explicitly factored anticipated La Niña impacts through February-March-April 2026. That meant regional temperature and precipitation tilts followed the classic La Niña playbook: above-normal precipitation odds for the Pacific Northwest, below-normal precipitation odds for the southern tier, and warmer-than-average conditions across much of the South. Those patterns are well documented in the historical record and give forecasters a reliable statistical starting point when a clear La Niña signal exists, especially for the late winter period when teleconnections tend to be strongest.
But the January discussion also flagged growing uncertainty as La Niña weakens into spring, an acknowledgment that the very foundation of those regional calls could shift within weeks. The CPC’s release calendar confirms that the next seasonal outlook issuance on February 19, 2026, will cover March-April-May and beyond. That update will need to reconcile the January framing, which leaned on La Niña teleconnections, with the February 12 diagnostic finding that ENSO-neutral conditions are now the base case. For regions like California’s Central Valley, where planting decisions and irrigation contracts hinge on spring precipitation expectations, even a modest shift in outlook probabilities can translate into real financial exposure and force last-minute adjustments in crop mix and water allocations.
Why Weak Events Muddle the Forecast
Not all La Niña episodes carry the same predictive value. Research summarized by NASA has shown that weak La Niña events yield less reliable teleconnections and are difficult to predict, precisely because the ocean-atmosphere coupling is too subtle to dominate the larger climate system. When the Nino-3.4 index hovers just below the La Niña threshold rather than plunging deeply negative, other drivers such as soil moisture anomalies, the Madden–Julian Oscillation, and Arctic pressure patterns can exert equal or greater influence on regional weather, sometimes overwhelming the ENSO signal altogether.
That dynamic matters for the spring outlook because the current La Niña has been weak throughout its lifecycle. The canonical U.S. impacts of a strong La Niña, a reliably wet Northwest and dry Southwest, lose statistical sharpness when the event barely qualifies. As the signal fades toward neutral territory, forecasters must weigh whether residual ocean cooling still tilts the odds or whether the atmosphere has already decoupled. The CPC’s advisory materials track observed metrics including Nino-3.4 indices, subsurface heat content, and wind and convection anomalies to make that call in near-real time, but the transition zone between La Niña and neutral is inherently noisy. In practice, that noise translates into more conservative probabilities on seasonal maps and a stronger emphasis on short-term climate drivers that can swing conditions on weekly to monthly timescales.
A New Monitoring Tool Arrives Mid-Transition
Complicating the picture further, the CPC has announced it is shifting its primary ENSO metric to the RONI, or Relative Oceanic Niño Index. The new index uses the ERSSTv5 dataset, defines the Niño-3.4 region, and applies tropical-belt subtraction along with variance adjustment to filter out background warming trends that have increasingly distorted the legacy Oceanic Niño Index. By removing part of the long-term warming signal, RONI is designed to highlight year-to-year variability more cleanly, giving a clearer picture of whether current anomalies truly resemble past El Niño or La Niña episodes.
The timing of this switch matters. Adopting RONI during an active transition from La Niña to neutral means that real-time monitoring, historical analog selection, and public communication are all being recalibrated at once. For forecasters, the new index offers a refined lens on how quickly the current event is decaying relative to earlier weak La Niñas in the 1950–present record. For users of the outlooks, from municipal water agencies to energy traders, it underscores that the metrics underpinning ENSO status are evolving alongside the climate system itself. As CPC staff integrate RONI into routine diagnostics, they will also need to explain how subtle differences between the old and new indices might affect perceptions of risk during shoulder seasons like spring.
Implications for Users of Spring Outlooks
The shift toward ENSO-neutral conditions does not erase the guidance value of seasonal outlooks, but it changes how that guidance should be interpreted. When La Niña was more firmly entrenched, many decision-makers could lean on the historical tendency for a wet Northwest and dry Southwest to shape contingency plans. As the ocean signal weakens, the same users may need to place greater weight on shorter-lead tools, such as monthly outlooks and subseasonal forecasts, which incorporate evolving atmospheric patterns more heavily than ENSO state alone. This layered approach is especially important for sectors like hydropower, where reservoir operations depend on both seasonal snowpack expectations and rapidly changing storm tracks.
For those seeking official information, the broader NOAA enterprise remains the central hub. National-scale climate outlooks and ENSO diagnostics are coordinated through NOAA’s climate programs, while operational forecast products are disseminated by the National Weather Service and its Climate Prediction Center. Public communication, including outreach on the limits of predictability during weak ENSO events, is supported by NWS information offices such as the Public Affairs division, which helps translate technical discussions into actionable guidance. As La Niña fades and neutral conditions take hold, that communication challenge will grow: the science can quantify shifting odds, but users must still navigate decisions under a wider cone of uncertainty.
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*This article was researched with the help of AI, with human editors creating the final content.
