Updated

The polar vortex high above the Arctic has reversed direction in the earliest major sudden stratospheric warming on record. Its winds usually blow westward and keep cold air locked over the North Pole, but BBC US & Canada reported that they weakened, shifted and switched to easterly flow. Such events often come in winter and are linked with colder weather, but this one came far earlier in autumn than any in modern observations. The previous earliest was on 28 November, in both 1969 and 2025. Forecasters are uncertain what the event means for winter weather. BBC US & Canada reported that experts have not determined whether it will bring an early taste of winter, and that any influence would take time to develop. The article said the possible effects on the United States and Canada are very uncertain, though past disruptions preceded the February 2010 Washington snowstorm and the deadly February 2021 Texas winter storm, both in late winter when such disruptions are most likely.