In 2015, the south polar stratospheric vortex has been unusually large, strong and persistent with polar cap temperatures below the 1979–2014 average during most of July, August and September and with record low temperatures in October. The low temperatures, together with the size of the vortex, have led to the formation of an ozone hole that can be compared to the large ozone holes observed in 1998, 2000, 2003 and 2006.
Data on the ozone hole area from the NASA Goddard Space Flight Center show that if averaged over the 60 worst consecutive days, 2015 has experienced the largest ozone hole ever seen. On the other hand, if one considers the amount of ozone destroyed, the so-called ozone mass deficit, the 2015 ozone hole is the fifth largest on record after 1998, 2000, 2001 and 2006.