The article presents the study results of thunderstorm activity with rainfall over a large territory of Western Siberia in its three regions: Northern, Central and Southern over a seven-year period from 2017 to 2023. The study revealed the most favorable synoptic conditions for the formation of thunderstorm activity with heavy rainfall over a large area of Western Siberia. Cases are also reviewed and factors that need to be paid attention to when forecasting thunderstorms with squally winds are identified.