WMO has published the first issue in the 2015 series of the Antarctic Ozone Bulletin, with information on the state of the ozone layer in Antarctica and surrounding areas. Measurements with ground-based instruments and with balloon sondes from some stations in the Global Atmosphere Watch network show first signs of ozone depletion, according to the bulletin. Satellite observations show that the area where total ozone is less than 220 DU (“ozone hole area”) has been significantly above zero since 18 August. This is a relatively late onset of ozone depletion. The ozone hole area on 27  August was approx. 5.1 million km2, about half the long-term average. The date of the onset of ozone depletion varies considerably from one year to the next, depending on the position of the polar vortex and availability of sunshine after the polar night. In 2015, the vortex has been relatively stable and concentric around the South Pole. This can explain the late onset of ozone depletion.