Research notes and updates from the team.
IRI’s NDJ 2026/27 outlook, shaped by a very strong El Niño (Niño 3.4 at +2.84°C in September, +3.3°C weekly) and a positive IOD, favors drier-than-normal conditions in northern South America, Central America, South Africa and Southeast Asia, and wetter conditions in the southern U.S., Uruguay and the Middle East. Above-normal temperatures are likely across most of the globe.
Read more →The IOD turned positive in September 2026 (DMI +0.51°C) after a neutral June–August. Models expect positive conditions to continue, peaking in November and weakening in December. Positive-phase odds are near 100% in October, 97% in November, and 74% in December, with neutral favored from January through April 2027.
Read more →A very strong El Niño is intensifying: weekly Niño 3.4 hit +3.3°C (Oct 14), with Niño 1+2 above +5°C and a very warm subsurface. All 27 models forecast a peak near +3.5°C in OND–NDJ. El Niño odds are 100% through MAM 2027, easing to 92% in AMJ and 60% in MJJ, then neutral becomes likeliest by JJA.
Read more →The IOD was neutral in August 2026 (+0.2°C) but models forecast a shift to strongly positive conditions starting September, peaking through December 2026, then easing back to neutral by Jan–Mar 2027. This positive IOD is emerging alongside the exceptionally strong El Niño, a common co-occurrence pattern between the two climate modes.
Read more →A very strong 2026 El Niño is intensifying, with Niño 3.4 hitting +3.0°C (mid-Sept) and subsurface heat surging. All 22 forecast models agree it will strengthen further, staying "very strong" through winter 2026–27. El Niño probability is 100% through Feb 2027, dropping to 61% by mid-2027. Could rank among the strongest El Niño events on record.
Read more →The forecast shows increased chances of below-normal rainfall in northern South America, Central America, South Africa, SE Asia, and the Maritime Continent, expanding to Alaska, NW Australia, and Madagascar by DJF–JFM. Above-normal rainfall is likely in the southern US, Uruguay, NE Africa, the Middle East, and parts of Eurasia—patterns broadly tied to strengthening El Niño conditions.
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