Total hit or miss. I spent five days in a tent in May of 2000, whiteout -30*C most nights. Got shut down 100' from summit by brutal winds, navigate down Athabasca by GPS.
The next year a buddy blitzed the thing in May and it was like +30*C, short sleeves and anything.
As the saying goes, if there's a cloud in the sky in Lake Louise, it's shitting on the icefield, or something like that
Hey Ray, where did all your photos and TRs go on bivouac.com