The results of ground-based microwave observations of ozone in the middle atmosphere in Apatity (67° N, 33° E) during three winters (2017–2018, 2018–2019 and 2019–2020) are presented. Long-term ozone observations were carried out during the period of minimum solar activity for cycles 24 and 25. A mobile microwave spectrometer with an operating frequency of 110.8 GHz was used in the measurements, which allows tracking the behavior of ozone in the middle atmosphere with a 15-min time resolution. The microwave ozone data from ground-based measurements are compared with the MLS/Aura onboard data. Ground and airborne data are compared with the data of contact measurements with ozonesondes at Sodankyla st. (67° N, 27° E). In addition, MLS/Aura data from mid-atmospheric temperature soundings are used to interpret perturbations in the ozone layer associated with sudden stratospheric warmings. A significant influence sudden stratospheric warming on the ozone vertical distribution at altitudes of 22–60 km was found. At the same time, the scale of mesospheric ozone variability (60 km) over Apatity is comparable or exceeds the known model calculations for assessing the impact of solar proton events and auroral electron precipitation on the ozone of the polar regions.