We will be there this June--the 1st through the 10th in a Jambo House 2 bedroom Standard view--I just switched us over from our home resort (SSR) last week. We loved SSR, but also want to try the others. We were there last June (2-11) and frankly, I was prepared for terrible heat, humidity, and crowds, but I must have worked my mind up for much worse than it really is because none of the three seemed bad to us. The temps were in the low to mid 90s everyday we were there, but it just didn't seem all that bad most of the time and I didn't feel like the humidity was awful. (And I have lived in the desert of Colorado all my life, so it's not like I'm used to it.) We used Fastpass and never waited more than about 20 minutes for anything and in early mornings experience many walk-ons.
I think I just saw so many posts about how awful and dreadful the summer months are, so I had prepared myself for torture and it just really wasn't that way at all.