We were there last year june 19th-23rd..It did rain just about everyday around 2 to 3 for an hour or so..While I thought it looked fun in the photos to do the parks in the rain, AK was not much fun in the rain (even with ponchos..) I just wanted out of the park..The showers cooled it off though, as right around that time, its reaching unbearable as far the heat. Cleaned things off for the night. If youre going to Florida, you may as well be hot, I say..
As for being crowded, we really didnt have much issue with that. Get your fastpasses early..Definitely get to the parks early. I dont know if we'll get the kids up and out to be able to make any ropedrops this year, but believe you me, IF I can, I will!
Good Luck!