Over the last almost six decades, there exist ever-increasing changes in tornado frequency over Ontario, Canada. It has been identified for the first time that there is a robust upward trend in tornado frequency, demonstrated through the MK test with consideration of removing a lag one autoregressive process. It is shown through a composite analysis that in the warming climate the tornado events occur more frequently over Ontario, especially under atmospheric conditions with stronger low-level cyclonic circulations, baroclinicity, and atmospheric convective instability.