NOAA Raises Late-2026 Very Strong El Niño Odds to 95% as RONI May Top 2.5C

3 articles · Updated · The Watchers · Aug 17

NOAA’s Climate Prediction Center lifted the chance of a very strong El Niño in October-December 2026 to 95%, up from 81% in July, with a 69% probability its RONI reaches at least +2.5C.
July Pacific data showed the event intensifying: Niño-3.4 sea-surface anomalies hit +1.4C, warm subsurface water reached localized +10.0C, and wind and convection patterns aligned with a strengthening coupled El Niño system.
NOAA’s median RONI forecast is +2.66C for October-December and +2.23C for December-February, keeping the central winter outlook in very strong territory even as ensemble spread leaves room for less extreme outcomes.
U.S. winter 2026-27 guidance increasingly points to a classic El Niño pattern—wetter conditions across much of the southern tier, drier weather from the Northwest into the northern U.S., and above-normal temperatures across much of the West and northern tier.
NOAA cautioned that even an extreme El Niño will not dictate individual storms, and teleconnections can shift or weaken depending on where tropical Pacific convection sets up and whether other basins, including the Indian Ocean, also warm.