The final warming in the Southern Hemisphere stratosphere during the period 1 September--30 November for the years 1978--1983 is studied. The change in zonally averaged temperatures during that period is almost the same for each year. However, there is substantial inter-annual variability in the time evolution of the warming as events of enhanced wave, mean-flow interaction associated with bursts of upward propagating planetary waves develop at different times in different years. Polar temperatures in the middle stratosphere can increase as much as about 20 K in 4 days during these events. Such dynamical processes can play a significant role in the interannual variability of stratospheric ozone and other constituents.