The El Niño climate phenomenon, which is continuing to grow and is by some measures already the strongest on record, may impact the UK's weather prospects this autumn and winter.
For the remainder of autumn, El Niño is expected to increase the chance of wet, mild, and potentially stormy weather across the UK. However, later in winter, it could shift the odds towards colder conditions and snow, a possibility that can be influenced by changes in the polar vortex, though this outcome is not certain.
The polar vortex is a ring of strong westerly winds encircling the North Pole, high above the Earth's surface. A strong polar vortex typically brings mild air from the Atlantic, while a weakened or disrupted vortex can lead to colder northerly or easterly winds in the UK.
While El Niño can release energy upwards through the atmosphere, making a polar vortex disruption more likely and increasing the chance of ice and snow later in winter, the links are described as unclear and the evidence mixed. For instance, the cold winter of 2009/2010 coincided with an El Niño, but the 2006/2007 El Niño winter was unseasonably warm. Current forecasts do not indicate significant cold or snow in the near future.