SUDDEN STRATOSPHERIC WARMING (SSW): WHAT INDIA & THE WORLD SHOULD WATCH

In recent weeks, climatologists have flagged a renewed Sudden Stratospheric Warming (SSW) event unfolding high above the Arctic — a development that could reshape weather patterns not only in the northern latitudes, but even impact regions as far-flung as South Asia.

What is SSW — and Why Does It Happen

SSW occurs when the normally frigid stratosphere over the Arctic experiences a rapid and dramatic rise in temperature — often by tens of degrees Celsius over a few days.
It is typically triggered by large-scale “planetary waves” — atmospheric waves originating in the lower atmosphere (troposphere) — that propagate upwards and disrupt the normally stable “polar vortex,” the stratospheric wind circulation encircling the polar region. \
In a major SSW, the zonal mean winds around ~10 hPa pressure (~30 km altitude) shift from eastward (westerly) to westward (easterly) — marking a “reversal” of normal stratospheric circulation. \

Recent Developments: 2025‑26 SSW and Polar Vortex Disruption

The winter of 2024–25 ended with a major SSW that abruptly dismantled the wintertime stratospheric polar vortex in the Northern Hemisphere.
New research shows SSW events can occur in clusters; during 2023–24, there were three distinct SSW episodes — two of them short-lived, and one a prolonged canonical warming lasting weeks.
The ability to forecast SSW events has recently improved, thanks to advances including a new “generative AI” model that can predict the onset, strength and structure of SSW up to 20 days in advance.

Global Impacts: From Polar Chill to Middle‑latitude Extremes

While SSW originates ~ 30 km above Earth’s surface, its effects can cascade down to influence weather — and even air chemistry — on the ground.

In the Northern Hemisphere, a disrupted polar vortex often results in the weakening or meandering of the jet stream. The result: cold Arctic air may surge southward, bringing colder and snowier winters, sometimes far from the Arctic itself.
There are also atmospheric‐chemistry effects: a 2025 study found that downward‑propagating SSWs (dSSWs) can trigger significant ozone intrusions over South Asia, increasing tropospheric ozone levels by as much as ~43 % within a month of SSW onset.
Such ozone intrusions can enhance radiative forcing (i.e. warming effect) over the region, with implications for air quality, human health and vegetation, especially in populated parts of South Asia.
Further, SSWs have been linked to disturbances in the ionosphere — potentially affecting satellite communication and radio systems.

What It Could Mean for India & South Asia

Although SSW originates in the Arctic, its “downward ripple” — via changes in atmospheric circulation and chemical mixing — can influence South Asian climate, especially in northern India. For policymakers and analysts it raises a few critical concerns:

Air Quality Surge: As the 2025 study shows, SSW‐induced ozone intrusion could elevate near‑surface ozone over South Asia — aggravating pollution and public‑health risks, especially in winter.
Unusual Weather Patterns: Though linking a single SSW to a specific rainfall or cold spell remains difficult, history suggests SSW events can sometimes disrupt monsoon/reversal patterns, or cause unseasonal rains or droughts.
Preparedness for Extremes: Given improved forecasting abilities (e.g. via AI models), meteorological agencies in India might monitor SSW developments closely, to anticipate downstream climate or air‑quality anomalies.

SSW — A Stratospheric Trigger with Earth‑wide Consequences

Sudden Stratospheric Warming may originate high above the Arctic, but its impact can reverberate far beyond — crossing hemispheres, influencing tropospheric air chemistry, jet streams, weather extremes, and even regional air quality over destinations as distant as South Asia. As climate change continues to alter wave dynamics and atmospheric circulation, SSW events — once rare curiosities — may become more consequential.

For a country like India — already vulnerable to air pollution, erratic monsoons, and extreme weather — better understanding and tracking of SSW could enrich the climate‑resilience toolkit.