Time variations in the polar mesosphere winter echo (PMWE) volume reflectivity and turbulent energy dissipation rates are examined during the sudden stratospheric warming (SSW) in September 2019 in the Southern Hemisphere. It was found that the frequency of PMWE occurrence decreased from early September to October, when the SSW occurred. We also found that the frequency of large turbulent energy dissipation rates (>3 × 10−4 m2s−3) was reduced compared to the average for 2016–2018. This is likely due to the modulation of gravity wave (GW) propagation by the minor SSW, resulting in less GW breaking, which is the main source of the turbulence. This suggests that the decrease in turbulence intensity is at least partly responsible for the decrease in the frequency of PMWE. Plain Language Summary Polar mesosphere winter echoes (PMWEs) are the coherent echoes from a height of 50–80 km observed by very high frequency clear‐air Doppler radars. We examine the time variations of PMWE and turbulence intensity associated with a sudden stratospheric warming in September 2019 in the Southern Hemisphere. We found that the PMWE occurrence frequency and turbulence intensity were reduced during and after the stratospheric warming. Assuming that the PMWEs are attributable to scattering echoes from turbulence in the ionized atmosphere, weak turbulence intensity will lead to a decrease in the frequency of PMWE. Furthermore, we discuss the reason why the stratospheric warming affects turbulence by performing a simple theoretical diagnostic of gravity wave propagation. Key Points A significant reduction in polar mesosphere winter echo occurrence was observed in the Antarctic after the stratospheric minor warming in 2019 Turbulent energy dissipation rates from radar spectral widths decreased after the minor warming Modulation of gravity wave propagation due to warming is likely the cause of the weakening of turbulence and a decrease in mesosphere echoes