Meteorologists say they are observing an unprecedented early disruption of the polar vortex, raising the risk of cold snaps across the Northern Hemisphere — though how severe any cold will be remains far from clear.
“As far as we know, this is the earliest stratospheric vortex disruption that has been observed,” European Centre for Medium-Range Weather Forecasts principal scientists Tim Stockdale and Frederic Vitart told AFP on Friday. The polar vortex is a vast region of cold, low-pressure air that normally circulates from west to east high above the Arctic, bottling up the coldest air near the pole.
A record that could fall by three weeks
Forecast models show stratospheric winds collapsing towards a full reversal in early November, splitting the vortex into two separate cores — one over Siberia and another over North America. If the reversal is confirmed, it would be the earliest sudden stratospheric warming on record by at least three weeks. The previous earliest event occurred on November 28, 1968, and a November warming has happened only three times in records dating back to the 1950s — in 1958, 1968 and 2025, all on November 28.
The ECMWF ensemble model put a 96 per cent chance on a wind reversal, according to Severe Weather Europe, while other models sat lower, at 71 per cent and 37 per cent. One forecast dashboard showed a full breakdown of the vortex — westerly winds turning easterly — by November 20. Confidence is higher for a substantial weakening than for the complete reversal needed to classify the event as a major warming.
What it means — and what it does not
A sudden stratospheric warming happens when temperatures in the polar stratosphere rise rapidly, sometimes by as much as 50°C within days, after large atmospheric waves surge upwards from below. The disruption usually takes one to four weeks to work its way down to the weather we feel, so any effects would most likely arrive as November turns into December.
But forecasters caution against assuming a deep freeze is coming. One AI ensemble forecast is very confident the winds will reverse, peaking around November 9, yet expects the event to be weak and short-lived — and keeps the eastern United States warmer than normal for the rest of November. A developing Super El Niño in the Pacific is adding uncertainty to the winter outlook, and longer-range forecasts suggest another, potentially stronger vortex disruption in mid-winter.
Closer to the ground, severe weather was already active. The National Weather Service issued tornado warnings on Friday for Sampson and Bladen counties in North Carolina, radar-indicated with no tornado confirmed on the ground at the time of reporting, and forecasters had warned of tornadoes possible in eastern New Mexico and west Texas, with a further risk on Monday in Oklahoma, north Texas and Kansas. Residents in affected areas were urged to keep a reliable way of receiving warnings overnight.
Related coverage: Wall Street Rebounds Friday as Nasdaq Rises After AI Rout | US Jobs Report: 165,000 Jobs Added as Unemployment Falls to 4.1%
