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The 2026 Antarctic ozone hole has surpassed 15 million km2 earlier than average and expanded to about 25 million km2 by mid-September, roughly 5 million km2 above the seasonal norm, Copernicus reports.
While its rapid growth is linked to colder stratospheric temperatures and polar clouds, other indicators remain near historical averages, underscoring complex ozone recovery dynamics.
With September 16 marking the United Nations International Day for the Preservation of the Ozone Layer, the Copernicus Atmosphere Monitoring Service (CAMS) has found that the 2026 Antarctic ozone hole reached a significant size threshold slightly earlier than average, aligned with 2025. It has also stayed ahead of average, unlike the previous year.
The 2026 Antarctic ozone hole has been developing at a typical rate since the second half of August, consistent with the previous 46 years. The area of this ozone hole reached 15 million km2 — more than the area of Antarctica — by the end of August 2026, which was slightly earlier than average and similar to development of last year’s ozone hole, which reached the same area on August 30, 2025.
In the first half of September, the area of this year’s ozone hole increased sharply, to an estimated 25 million km2on September 12 — around 5 million km2 above the average for this period — with forecasts showing a possible further increase in area in mid-September. Ozone depletion in the Southern Hemisphere stratosphere occurs as cold temperatures allow the formation of polar stratospheric clouds, which play a role in activating the chemical removal of ozone via halogens in the presence of sunlight during the austral Spring (August to November). The rapid development of the 2026 ozone hole coincided with a sudden decrease in the minimum temperature at approximately 20km above the south pole (50 hectopascal / hPa).
However, other ozone hole diagnostics monitored by CAMS, including the ozone column minimum value within the defined area of the ozone hole and the ozone mass deficit, remained close to the average values.
“The Antarctic ozone hole’s development can vary considerably from year to year, depending on a range of atmospheric and chemical factors. While we have seen its area increase rapidly in early September this year, other indicators remain close to historical averages. These findings highlight the importance of monitoring the complicated interaction between human-made disturbances and natural factors. CAMS provides the high-quality data, forecasts and analyses needed to understand the state of the ozone layer and track its long-term recovery.” Laurence Rouil, Director of CAMS.
The ozone layer protects life on Earth against harmful ultraviolet (UV) radiation, a major cause of skin cancers, by absorbing much of it. Over almost half a century, human-caused emissions have resulted in the thinning of this protective layer, putting people at risk. Additionally, global warming tends to cool the stratosphere, which favours the formation of polar stratospheric clouds which, in turn, play a key role in ozone depletion. The thinning of the ozone layer is most pronounced over the Antarctic — where the area of low pressure and cold air (polar vortex) and stratospheric winds are more stable — with the ozone hole there opening each year during the austral Spring.
The Antarctic ozone hole, which has been monitored by ground-based and satellite observations since the late 1970s, spanned a record 29.6 million km2 on September 9, 2006. It also covered its largest average area over a consecutive multi-week period in that month. However, recent years have seen smaller and shorter-lived ozone holes, indicating recovery.