The dependence of Antarctic ozone depletion on midlatitude planetary wave activity and South Pole temperatures was examined from 1979--2003 using NCEP/NCAR reanalyses and column ozone data. The annual severity of Antarctic ozone depletion was quantified using the seasonal mean of daily ozone mass deficit (OMD). The dependence of annual mean OMD on effective equivalent stratospheric chlorine (EESC) was removed to produce an anomaly time series (OMD'). Similar anomaly time series for 100 hPa South Pole temperatures (T') and 20 hPa, 60¿S midlatitude planetary wave activity (PWA') were calculated. Regression of OMD' against T' and PWA' shows that most of the interannual variability in Antarctic ozone depletion can be explained by variability in midlatitude planetary wave activity and South Pole temperatures. To estimate how future changes in South Pole temperatures, midlatitude wave activity and EESC will affect Antarctic ozone depletion, the regression model was applied to T' and PWA' values from a chemistry-climate model run (1975--2019).