Scientists from NOAA and NASA have reported that the 2025 ozone hole over Antarctica is the fifth smallest since 1992, when the Montreal Protocol began phasing out ozone-depleting chemicals. Warmer stratospheric temperatures and declining chlorine levels contributed to its limited size. The hole is already breaking apart nearly three weeks earlier than average.
The ozone hole peaked from September 7 to October 13, 2025, covering an average area of 7.23 million square miles, or 18.71 million square kilometers. On September 9, it reached its maximum single-day extent of 8.83 million square miles (22.86 million square kilometers), about 30% smaller than the record size in 2006, which averaged 10.27 million square miles (26.60 million square kilometers).
In the 46-year satellite record starting from 1979, this year's hole ranks as the 14th smallest by area. Paul Newman, a senior scientist at NASA's ozone research team, stated, "As predicted, we're seeing ozone holes trending smaller in area than they were in the early 2000s. They're forming later in the season and breaking up earlier."
Measurements show the ozone layer over the South Pole dropped to a minimum of 147 Dobson Units on October 6, compared to the all-time low of 92 Dobson Units in 2006. Stephen Montzka from NOAA's Global Monitoring Laboratory noted, "Since peaking around the year 2000, levels of ozone depleting substances in the Antarctic stratosphere have declined by about a third relative to pre-ozone-hole levels."
Newman added that without the chlorine reduction, the hole would have been over one million square miles larger. A weaker-than-normal polar vortex in August kept temperatures above average, aiding the smaller size, according to NOAA meteorologist Laura Ciasto.
The Montreal Protocol's restrictions on chemicals like chlorofluorocarbons continue to drive recovery, with full restoration to pre-depletion levels projected for the late 2060s as legacy emissions fade. Monitoring relies on satellites such as NASA's Aura and NOAA's polar-orbiting platforms, plus ground-based instruments at the South Pole.