The 2026 Antarctic ozone hole reached its seventh-largest size on record, driven by an unusually strong polar vortex, while scientists say the ozone layer continues to recover.
NASA and NOAA reported that the 2026 Antarctic ozone hole expanded to a size not seen in a decade, reaching its maximum extent on September 18, 2026, at 10.5 million square miles (27.1 million square kilometers).
The ozone hole ranked as the seventh-largest in 48 years of observations based on its average seasonal area. Between September 7 and October 13, 2026, when ozone depletion was at its seasonal peak, the hole covered an average of approximately 9.6 million square miles (25 million square kilometers), which is more than twice the size of the United States. The maximum extent on September 18 was approximately 90% of the size of the largest ozone hole ever measured, which occurred on September 9, 2000.
Scientists attributed the expansion primarily to an exceptionally strong polar vortex, a large circulation of winds that influences atmospheric conditions over Antarctica. "The polar vortex was unusually large this year in part because planetary-scale weather systems that typically well up from the lower atmosphere and break up the vortex were especially weak in August and September," said Amy Butler, a research scientist at the NOAA Chemical Sciences Laboratory. "That weak wave action kept the strongest polar vortex winds further from the South Pole by several degrees of latitude, creating a larger area for conditions ideal for ozone depletion to occur."
Despite the striking increase, scientists from NASA and NOAA say Earth's protective ozone layer is continuing its gradual recovery and remains on track to heal later this century. "The annual ozone hole has been forming later in the season in recent years, which tells us the ozone layer is healing," said Paul Newman, a senior scientist at the University of Maryland and longtime leader of NASA's ozone research team at the agency's Goddard Space Flight Center. "But an unusually powerful polar vortex has extended ozone depletion in the Antarctic this season, allowing the hole to grow to proportions we haven't seen in a decade."
Newman also said the 2026 ozone hole is large but could have been 1 to 2 million square miles (3.5 million square kilometers) larger if ozone-depleting substances were as prevalent in the atmosphere today as they were at their year 2000 peak.
NOAA researchers launched instruments attached to weather balloons from the South Pole Baseline Atmospheric Observatory and collected readings using the Dobson Ozone Spectrophotometer. Their observations showed that ozone levels directly above the South Pole fell to their lowest reading of 2026 on October 17, reaching 105 Dobson units. The lowest ozone concentration ever measured over the South Pole was 92 Dobson units in October 2006. Satellite data from NASA's Aura satellite, NOAA-20, NOAA-21, and the Suomi National Polar-orbiting Partnership satellite also contributed to the measurements.
Scientists expect the Antarctic ozone hole to recover by the 2070s.
Sources
This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.
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