The Arctic polar vortex shows its earliest major weakening in modern observations

The band of strong westerly winds roughly 30 kilometers above the Arctic normally strengthens through autumn and peaks near January, but it weakened sharply and may split in early November 2026. A University of Reading expert says no sudden stratospheric warming this early appears in satellite records since 1979 or reasonable earlier records; only three November events are known, in 1958, 1968 and 2025, all on November 28. ECMWF modeling currently points to a possible wind reversal around November 20. A very strong El Niño and high pressure over Scandinavia and northwestern Russia are candidate causes, not settled explanations. A weaker vortex increases midlatitude cold-outbreak risk but cannot guarantee snow or severe cold for any city, so energy, transport and agriculture should treat it as an early warning rather than a deterministic forecast.