NOAA and NASA report that the 2025 ozone hole over Antarctica was far smaller and shorter-lived than usual. Falling chlorine levels and a weaker polar vortex helped limit ozone loss this season.

These findings add to decades of evidence showing that the Montreal Protocol is working. Scientists expect the ozone layer to keep strengthening in the coming decades.

2025 Antarctic Ozone Hole Ranks Among Smallest in Decades
Scientists at NOAA and NASA report that this year’s Antarctic ozone hole is the fifth smallest measured since 1992 — the same year the Montreal Protocol began reducing the use of ozone-depleting chemicals.

During the peak of the 2025 ozone depletion season, which lasted from September 7 through October 13, the ozone hole covered an average of about 7.23 million square miles (18.71 million square kilometers). It has also begun to break apart almost three weeks earlier than the typical timing seen over the past ten years.

“As predicted, we’re seeing ozone holes trending smaller in area than they were in the early 2000s,” said Paul Newman, a senior scientist at the University of Maryland system and longtime leader of NASA’s ozone research team. “They’re forming later in the season and breaking up earlier.”