Overview
- NOAA and NASA released coordinated measurements on Nov. 4, 2026 showing the seasonal mean ozone‑hole area was about 9.6 million square miles and that the one‑day maximum reached 10.5 million square miles on Sept. 18.
- Scientists attribute the large 2026 extent to an unusually large polar vortex and weak planetary‑scale waves in August and September that kept cold, ozone‑destroying conditions over a wider area.
- Despite its size, the 2026 hole was not unusually deep: balloon and ground observations found a minimum column value of about 105 Dobson units on Oct. 17 versus a historical low of 92 Dobson units in 2006.
- Researchers combined satellite data from NASA and NOAA platforms with balloon‑borne ozonesondes and ground instruments to produce the assessment and to track both area and depth of depletion.
- Agencies say controls under the 1987 Montreal Protocol have reduced stratospheric chlorine by roughly one third since the 1980s and that the ozone hole is expected to recover by about the 2070s as legacy chemicals break down.