Here is my 100% Achievement guide for Hardcube!
In all honesty, this is probabaly unmissable as there are plenty of wind happenings that can blow you off the screen.
BUT, its always best to get it out the way early, so you can see where i do it on my video at 14:10.
Simply wait for the gust of white wind to happen, then jump into it to knock you off.
Hope This Helps!