The Antarctic ozone hole ranked seventh-largest in 48 years of monitoring by seasonal mean area, NOAA and NASA reported November 4. Scientists attributed the unusually large 2026 season to weather conditions, while maintaining that long-term recovery remains on track.

The average area during September 7 through October 13 was about 25 million square kilometres. Its greatest extent, reached September 18, was 27.1 million square kilometres. The seasonal average and single-day maximum are different measurements.

A strong polar vortex prolonged conditions favorable to ozone loss. The agencies report that reductions in ozone-depleting chemicals prevented an even larger hole. Their assessment therefore distinguishes a difficult individual season from the effect of sustained international controls on those substances.

Ground observations and satellite instruments contribute to the monitoring. NOAA measured the year’s lowest overhead South Pole ozone concentration, 105 Dobson units, on October 17. The report interprets earlier observations, not a hole opening today. Scientists continue to estimate recovery by the 2070s.