6 January 2021 (WMO) The record-breaking 2020 Antarctic ozone hole finally closed at the end of December after an exceptional season due to naturally occurring meteorological conditions and the continued presence of ozone depleting substances in the atmosphere.
The 2020 Antarctic ozone hole grew rapidly from mid-August and peaked at around 24.8 million square kilometres on 20 September 2020, spreading over most of the Antarctic continent.
It was the longest-lasting and one of the largest and deepest holes since the ozone layer monitoring began 40 years ago. It was driven by a strong, stable and cold polar vortex and very cold temperatures in the stratosphere (the layer of the atmosphere between around 10 km and round 50 km altitude). The same meteorological factors also contributed to the record 2020 Arctic ozone hole.