Federal forecasters are warning that a strengthening El Niño pattern will push the United States into a summer defined by two simultaneous threats: an unusually active eastern Pacific hurricane season and temperatures that could place 2026 among the five warmest years in recorded history. The Climate Prediction Center, working alongside the National Hurricane Center, the Central Pacific Hurricane Center, and NOAA’s Atlantic Oceanographic and Meteorological Laboratory, has issued its 2026 Eastern North Pacific Hurricane Season Outlook with El Niño conditions expected to fuel storm development. At the same time, NOAA’s National Centers for Environmental Information projects 2026 is very likely to rank among the five warmest years on record, building on 2024’s distinction as the warmest year in NOAA’s global temperature record since 1850.
Warmer Pacific waters and a dual summer threat
The connection between El Niño and eastern Pacific storm activity is direct. Warmer-than-normal sea surface temperatures reduce wind shear and increase atmospheric instability across the basin, creating conditions that favor tropical cyclone formation. The CPC’s official outlook for the 2026 season, produced in collaboration with NHC, CPHC, and AOML, explicitly states that El Niño conditions are expected during the eastern North Pacific hurricane season. That finding carries weight because it draws on NOAA’s newly adopted Relative Oceanic Niño Index, or RONI, which uses a 1991–2020 baseline and applies a variance adjustment to filter out long-term ocean warming trends that could inflate older metrics.
The stage-1 hypothesis tested here is straightforward: if RONI remains above +1.0 degrees Celsius through July 2026, eastern Pacific named-storm counts should finish at least 25 percent above the 1991–2020 median, independent of any single seasonal outlook statement. Historical El Niño episodes that reached moderate or stronger intensity have consistently produced above-average storm seasons in the eastern Pacific, and the current trajectory aligns with that pattern. CPC released official ENSO strength probabilities by season in June 2026, breaking the forecast into neutral, weak, moderate, strong, and very strong categories using RONI thresholds of plus or minus 0.5 degrees Celsius.
The heat side of the equation is equally concrete. NCEI’s Global Annual Temperature Outlook, published as part of its April 2026 analysis, states that 2026 is very likely to rank among the five warmest years. That projection sits on top of 2024’s record: the warmest year in NOAA’s global temperature record dating to 1850, as detailed in NCEI’s summary of the recent global climate. The CPC’s seasonal outlook for June through August 2026 draws on NMME and Copernicus multi-model ensembles, statistical tools, soil moisture data, and long-term trends to project elevated odds for above-normal temperatures across much of the contiguous United States.
How RONI replaced the old index and what the models show
NOAA’s transition from the older Oceanic Niño Index to RONI is not a minor technical update. The RONI methodology calculates a three-month running mean of ERSSTv5 Niño-3.4 anomalies, subtracts the tropical mean, and applies a variance adjustment. That adjustment matters because it strips out background warming that has been steadily raising baseline ocean temperatures, making it harder to distinguish genuine El Niño events from the general upward drift in sea surface temperatures. NOAA’s Physical Sciences Laboratory has also confirmed the agency is replacing ERSSTv5 with ERSSTv6, a dataset upgrade that will further refine how ENSO episodes are classified and measured.
The CPC’s seasonal outlook discussion covering June–July–August 2026 through June–July–August 2027 lays out the analytical framework behind the summer temperature forecast. The agency blends output from the North American Multi-Model Ensemble and the Copernicus multi-model system with statistical downscaling, soil moisture observations, and long-term climate trends. When soil moisture is already depleted heading into summer, as it is across parts of the southern Plains and Southwest, the feedback loop between dry ground and high temperatures intensifies. Heat that would normally go into evaporating soil moisture instead warms the air, pushing daytime highs further above average.
For coastal communities along the Pacific coast and in Hawaii, the storm outlook carries practical urgency. El Niño episodes tend to shift tropical cyclone tracks closer to the coastline and extend the window during which storms maintain intensity at higher latitudes. Residents in these areas face a compressed timeline to prepare, because the eastern Pacific hurricane season runs from mid-May through November and the strengthening El Niño signal suggests the most active period could arrive earlier than in neutral years. Emergency managers are emphasizing the need for updated evacuation plans, backup power options, and clear communication strategies before the peak months of August and September.
Gaps in the forecast and what to watch next
Several pieces of the picture remain uncertain, even with a strong El Niño signal in place. Seasonal hurricane outlooks can estimate how many storms are likely to form across the basin, but they cannot reliably identify which storms will make landfall or which stretches of coastline will be most at risk. A season with many storms can still spare the mainland if steering currents keep systems offshore, while a comparatively quiet year can become destructive if even one major hurricane strikes a heavily populated area.
On the temperature side, forecasters also grapple with regional nuances that broad global rankings cannot capture. Even if 2026 finishes among the five warmest years globally, some parts of the United States could see near-normal or even slightly cooler conditions for portions of the summer, depending on local storminess, soil moisture, and atmospheric circulation patterns. The CPC’s multi-model blends highlight a strong tilt toward warmth, but they also show pockets of greater uncertainty where model agreement is weaker or where short-term weather patterns can overwhelm the seasonal signal.
Another wildcard is how the atmosphere will respond to the evolving ocean state beyond the core El Niño region. The tropical Atlantic, the Indian Ocean, and high-latitude sea ice conditions all influence the jet stream and the placement of high- and low-pressure systems. Those, in turn, shape heat waves, droughts, and storm tracks over North America. While RONI helps isolate the El Niño component more cleanly than older indices, it does not capture every driver of seasonal climate variability.
Forecasters are watching several markers as summer progresses. One is whether RONI values plateau, strengthen, or begin to decline heading into late summer, which could subtly shift the odds for late-season storm development. Another is soil moisture evolution across the central and eastern United States. A wet spring can temporarily blunt extreme heat, but rapid drying under strong sun can flip the script and set the stage for intense late-summer heat waves.
For households, businesses, and local governments, the message from federal agencies is not to fixate on exact storm counts or temperature rankings, but to plan around the heightened risk envelope that a strong El Niño creates. Along the Pacific coast and in Hawaii, that means reviewing building codes, assessing coastal erosion, and ensuring that shelters and critical infrastructure can withstand prolonged wind and rain. Inland, it means preparing for more frequent or longer-lasting heat waves, with particular attention to vulnerable populations such as older adults, outdoor workers, and people without reliable access to air conditioning.
In the coming months, updates from CPC and NCEI will refine the outlook as new data arrive and as the coupled ocean–atmosphere system reveals how closely reality is tracking the models. The broad contours, however, are already clear: a warmer Pacific, a busier eastern Pacific hurricane season, and a global climate baseline that makes extreme heat more likely. Together, they point toward a summer in which preparation and flexibility will matter as much as the precise trajectory of any single storm or heat wave.
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*This article was researched with the help of AI, with human editors creating the final content.
