Reported by BBC Science
High above the Arctic, powerful winds usually circle the North Pole each winter, helping trap some of the coldest air on Earth.
But this circulation, known as the polar vortex, has weakened and shifted position in recent days.
While such disruptions can occur during winter, scientists say an event this early in November is unprecedented in modern observations.
More from the original report
Similar disruptions in past years have sometimes been followed by colder weather affecting parts of Europe and North America.
However, as this is happening so early in the season, there are few historical examples to compare with and it could throw current winter forecasts into even more uncertainty.
The polar vortex develops every autumn as temperatures fall in the Arctic.
Strong westerly winds form in the stratosphere, roughly 10 to 30 miles (15-50km) above Earth's surface, locking the coldest air near the pole.
Atmospheric disturbances can cause the air high up to start warming which then makes the vortex winds weaken. This sudden stratospheric warming (SSW) can eventually lead to the strong westerlies reversing into easterly winds.
In the following days and weeks these changes can alter the position of the jet stream, increasing the chance of a blocked weather pattern where it can become drier with a colder northerly or easterly wind bringing Arctic air in.
It can also boost the possibility of snow, especially in eastern UK.
Most SSW events tend to occur from mid-winter but we are currently witnessing a dramatic weakening of the strong winds with some forecasts even showing a reversal of the polar vortex winds by mid-November.
Due to this weakening, the vortex has stretched and briefly split into two smaller circulations around the Arctic.
Sudden stratospheric warming can lead to a weakening of the polar vortex, resulting it in becoming disrupted, even split, high above the Arctic region
If the winds continue to weaken and end up reversing as forecast, this will be known as a major SSW event.
Jeff Knight, lead climate scientist from the Met Office, told the BBC: "It would appear to be the earliest on record looking back over the 75…