Overview
- The Climate Prediction Center kept its La Niña advisory in place, saying the event that began in October will continue to guide U.S. weather through the heart of winter 2025–2026.
- NOAA reported the Niño‑3.4 index at −0.5°C in early December and forecasters judge La Niña near its peak with a transition to neutral conditions favored in the January–March window.
- Seasonal guidance points to a drier southern tier and wetter northern tier, with higher snow odds in the Pacific Northwest, northern Rockies, Great Lakes and the interior Northeast.
- Forecasters expect a polar‑vortex‑driven cold outbreak in mid‑December to give way to a more typical La Niña pattern late December into January, with some regions briefly turning milder before colder spells return.
- CPC notes growing yet sub‑50% odds of El Niño in mid to late 2026, citing a warm western Pacific pool that could enable a rapid flip if westerly wind bursts occur, though scientists emphasize considerable uncertainty.