weather, I spent one week in the Bannf area and one week in Glacier National Park. It rained almost every day. It was probably my own fault. Mid June both trips.
I would say your perception is right on, particularly for June....but I live here and this is all I do, so easy for me to switch around my objectives depending on the sweet spot(s)...when I did Watch Tower the other day, it was pouring down rain every where else...we really study the forecasts and move around accordingly...bad weather and rock fall are perilous in the Canadian Rockies.