This applies even more so in the Great White North.

We are currently (ie apr 8) having a warm spring but it can change instantly.

I have seen 50cm of snow on the Banff-Radium highway two days before the Golden Triangle tour (May 24 approx) and fresh snow on the Banff-Jasper road in mid June.

If you are planning on camping in the Canadian Rockies on your cycle tour wait until at least June
and even then be prepared for snow.