What are the latest global climate model forecasts for december 2025 and january 2026
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Executive summary
Global seasonal model ensembles agree on a La Niña-influenced winter for December 2025 (NDJ/DJF) with elevated odds of above‑normal land surface temperatures across much of the Northern Hemisphere and a strong west–east Pacific SST gradient; multi‑model products show La Niña most likely to persist through December–February 2025/26 but transition to ENSO‑neutral by early 2026 (CPC 55–68% / IRI 53%) [1] [2] [3] [4]. WMO and Copernicus‑aligned forecasts emphasize widespread above‑normal temperatures and regional precipitation shifts (suppressed central/eastern Pacific rainfall, enhanced western Pacific rainfall), while national products (NOAA/CPC) and regional analyses show expected regional variability such as increased snowfall potential in parts of North America if polar vortex disruptions occur [1] [2] [5] [4] [6].
1. La Niña is the headline driver — but probably weak and short-lived
Global multi‑model ensembles and the CPC/IRI diagnostics indicate SST anomalies in Niño‑3.4/3 are forecast to decline toward a weak La Niña for NDJ/DJF 2025/26, with models assigning roughly a majority chance for La Niña to hold through boreal winter and a transition to ENSO‑neutral by January–March 2026 (IRI: La Niña favored through Dec–Feb ~53%; CPC: La Niña favored next month or two, neutral likely Jan–Mar 2026 ~68%) [3] [4]. WMO seasonal updates echo this: a weak La Niña pattern is expected but with persistent warm western Pacific SSTs that sustain an east–west gradient and La Niña‑like atmospheric responses [1] [2].
2. Global temperature outlook: persistent warmth, record‑near years likely
The multi‑model seasonal outlooks show a strong signal for above‑normal land surface temperatures across much of the Northern Hemisphere for NDJ/DJF 2025/26; WMO’s decadal update also projects 2025–2029 annual means 1.2–1.9°C above 1850–1900 and says there is high probability that one of these years will exceed the current record [1] [5]. Copernicus‑aligned forecasts and Climate Central note elevated Arctic and North Pacific temperature anomalies through the season [7] [8].
3. Precipitation patterns: La Niña fingerprints and regional nuance
Seasonal precipitation forecasts reflect a La Niña‑like pattern: suppressed rainfall across the central/eastern equatorial Pacific and enhanced rainfall over the western Pacific and adjacent land areas; this produces regionally contrasting wet/dry signals globally rather than uniform outcomes [1] [2]. National and independent analyses translate those large‑scale tendencies into local expectations — for example, ensemble forecasts and long‑range guidance show elevated snowfall potential in parts of northern US and Canada and wetter conditions in western Pacific‑influenced regions when moisture and dynamics align [6] [2].
4. North America and Europe: probabilistic split, polar vortex can alter the story
NOAA/CPC seasonal color maps and subsequent commentary point to a split pattern across the continental U.S. — cooler in some northern sectors and warmer in large southern/eastern areas — with the caveat that stratospheric/ polar vortex disruptions can drive colder outbreaks and increased snow in mid‑latitudes despite the La Niña background [9] [6] [10]. Independent long‑range products have adjusted to show more snow and earlier cold signals for December with persistence into January in some scenarios tied to vortex collapse [6] [10].
5. Uncertainty and limits: probabilistic forecasts, spring barrier, and regional translation
All cited products are probabilistic and present tercile‑based likelihoods rather than deterministic weather. ENSO forecasts become notably less certain across the spring predictability barrier; IRI explicitly notes uncertainty beyond DJF and rising chances of ENSO‑neutral by Jan–Mar 2026 [3]. WMO and Copernicus materials stress model agreement on large‑scale temperature tendencies but emphasize regional variability; high‑resolution regional impacts remain sensitive to boundary conditions from the global models and to internal atmospheric events [1] [2] [11].
6. What the public should expect and how forecasters will update
Expect frequent updates: CPC/IRI/WMO seasonal products and national outlooks will be revised monthly as ocean and atmospheric observations change and as stratospheric or other dynamical events occur. For practical planning, use ensemble probabilistic outlooks for broad risk framing (higher odds of above‑normal temperatures, La Niña‑consistent precipitation shifts) and consult national/regional agencies for locally downscaled guidance and short‑term updates tied to polar vortex or storm developments [4] [1] [2].
Limitations: available sources do not mention precise day‑by‑day weather for December 2025 or January 2026, nor do they present a single unified “global climate model forecast” — instead they offer multi‑model ensemble probabilities and regional interpretations that evolve monthly [1] [3] [4].