Forecasts suggest that weakening and eventually reversing winds could produce a major south-southwest sudden stratospheric warming (SSW) event, potentially the earliest recorded during 75 years of observation. The event may be linked to the current strong El Niño, but scientists stress that the relationship is uncertain and requires further research.
Geoff Knight, the Met Office’s chief climate scientist, told the BBC: “This appears to be the earliest on record over the 75 years we’ve been observing…Most experts agree this is a very rare event.”
The earliest major SSW events recorded to date occurred on November 28 in both 1969 and 2025.
What causes sudden stratospheric warming?
It is not clear why major SSW events can occur so early in the season. They may simply reflect natural variability in weather patterns.
However, scientists know that during “normal” El Niño years, the phenomenon can weaken the polar vortex, potentially affecting winter weather.
El Niño’s unusually warm Pacific waters directly influence weather patterns in the tropics. At the same time, pulses of atmospheric energy known as planetary waves can disrupt conditions in the polar regions.
These waves can displace the polar vortex and interfere with its circulation. The polar vortex is a large area of cold air and low pressure that forms in the stratosphere around the poles.
Uncertain connection to El Niño
The current record-setting El Niño is producing unprecedented disruption to global weather patterns. Knight suggested that El Niño “could have helped stack the dice on this south-southwest event. But this is so rare that there isn’t enough evidence.”
The relationship between a strong El Niño and the early onset of SSW events remains unclear and will require further research.
Source: www.bbc.co.uk