Atypical Antarctic ozone hole maximum. Satellite image of the maximum extent in 2019 of the ozone hole (blue) over Antarctica (centre). Ozone layer thicknesses are colour coded from purple (lowest) through blue, cyan and green to yellow (highest). The ozone hole reached its annual maximum on 8 September 2019, covering an area of many million square kilometres. The 2019 peak (and its aftermath) was smaller and atypical for recent years, due to unusually strong weather patterns that caused warm temperatures in the upper atmosphere above the South Pole region of Antarctica. This is the third time in the last 40 years (after 1988 and 2002) that weather systems have caused warm temperatures that limit ozone depletion. Long-term, the amount of ozone-depleting substances have decreased from peak levels in 2000. NASA has been monitoring the status of the ozone layer through satellite observations since the 1970s. Image data obtained by the Ozone Monitoring Instrument on NASA's Aura satellite.