The results of field experiments to assess the possible influence on seismic safety of structures of seasonal changes in the resonant properties of the underlying subsurface soils are given. The natural frequencies of a ten-story residential building and the surface soil layer were determined from passive (noise) seismic acoustic measurements made at the end of January and the end of June. The results of the experiments showed that in areas with climatic conditions characterized by alternation of long periods of positive and negative temperatures, the resonance properties of the surface soil layer during the year can vary more significantly than the properties of the structures built on them. At certain periods, such changes can lead to the coincidence of some natural frequencies of the soil layer and the structures standing on it, which ultimately  reduces their seismic safety.