2026 Antarctic ozone hole reaches annual maximum area

NASA said on Monday 09 November 2026 that the Antarctic ozone hole reached its annual maximum area on September 18. The agency said the 2026 hole was the seventh largest in 48 years of monitoring by mean size from September 7 to October 13. It was not as deep as other large holes on record.

An unusually strong Antarctic polar vortex created ideal conditions for ozone depletion over a large area. NASA said colder conditions result in a larger ozone hole and lower ozone values in its core. Year-to-year changes in area and depth are caused by variations in stratospheric temperature and circulation.

NASA maps show the ozone hole on the day of its maximum depth, when the lowest ozone concentrations were measured. The agency said the term hole is a metaphor for the area where ozone concentrations fall below the historical threshold of 220 Dobson Units. No place is empty of ozone.

NASA said the 2026 measurements were made by the OMPS on the NOAA-20 satellite. Its data visualizations show the ozone hole each year from 1979 through 2026. No data are available for 1995. Red and yellow areas indicate the ozone hole.

The deepest ozone hole occurred in 1994, when concentrations fell to 73 DU on September 30. NASA said records in depth and area have never occurred in the same year. The largest ozone hole occurred in 2006.

NASA said scientists estimate that about 80 percent of the chlorine in the stratosphere comes from human sources. The 1987 Montreal Protocol led to a treaty phasing out the consumption and production of ozone-depleting chemicals. Scientists estimate that the Antarctic ozone layer will return to 1980 levels in the 2070s.