The title is referring to a specific heatwave that just occured, not the possibility of any heatwave at all ever happening in North America. That means the spec

The title is referring to a specific heatwave that just occured, not the possibility of any heatwave at all ever happening in North America. That means the specific parameters and temperature variations are part of the discussion. In this case, the temperatures in Canada surpass those numbers both in the absolute and relative to norm.