Stratospheric Warming Event May Be Unfolding In The Southern Polar Vortex, Shaking Up Global Weather Systems

Both of Earth’s poles are surrounded by a circling, swirling mass of cold air in the stratosphere, located between approximately 12 and 50 kilometers (7.5 and 31 miles) above the surface. Known as polar vortexes, the flow of air helps to trap the colder air near the poles. Compared to the Arctic one in the north, the southern vortex over Antarctica is stronger, larger, and longer-lasting.

Under certain conditions, these systems can become looser and more unstable. The winds that enforce the polar vortex can weaken, allowing cold air to spill into lower latitudes.

Now, some weather analysts believe early signs of this process may be appearing over Antarctica. According to data from NASA’s stratospheric monitoring system analyzed by Severe Weather Europe, the Southern Polar Vortex is showing all the telltale signs that a warming event is near: declining wind speeds, combined with rising temperature and pressure.

The Southern Hemisphere’s polar vortex always weakens during spring as part of its normal seasonal cycle. However, the data shows the current weakening is occurring much earlier and more sharply than usual, hinting that a stratospheric warming event may be emerging.

While such “sudden stratospheric warming” events are relatively common in the Northern Hemisphere, they are far less frequent in the south, because its flow is not disturbed by as many obstacles like mountains and complex terrain. 

It’s not always easier to predict how each stratospheric warming episode will impact weather patterns, and there’s no guarantee it will result in dramatic impacts on the ground. 

However, according to the DTN weather forecasting service, it’s likely that southern Australia will see more active cold fronts and low-pressure systems during the mid-to-late spring. Simultaneously, though, the same region might experience more early-season heatwaves and abnormally hot days. Rainfall is more likely in southern Australia, while it is less likely in eastern Australia.

Further afield, the effects are even harder to foresee, but it’s possible the event will impact global weather patterns. In September 2019, a record-breaking stratospheric warming event unfolded over Antarctica, which was so powerful that it had impacts on the opposite hemisphere. In its wake, scientists noted total electron content anomalies over North America and Europe, which they directly linked to the upset over Antarctica.

Forecasts for 2025 don’t suggest anything on the same scale as 2019. Nevertheless, that episode serves as a reminder that disruptions in the Antarctic stratosphere can ripple far beyond the South Pole across the globe.