Barb,
June is hot AND wet.
Now that's not to say it will rain every day that you are there but during the warm months it rains frequently in the late afternoon. Really big thunderstorms and can come quickly and sometimes leave just as quickly.
June is also humid - no matter what. I will tell you this though, in my opinion, July and August are the worst.
One other thing I would like to add is that the parks are open later during the summer and the late afternoon/early evening thunderstorms are just that and they don't go on all night usually.
I copied this from weatherchannel.com
Month Avg. High Avg. Low Mean Avg. Precip. Record High Record Low
Jan 72°F 48°F 60°F 2.39 in. 90°F (1962) 19°F (1985)
Feb 73°F 49°F 61°F 2.72 in. 90°F (1962) 27°F (1996)
Mar 77°F 53°F 65°F 3.32 in. 92°F (1964) 25°F (1980)
Apr 82°F 58°F 70°F 2.02 in. 98°F (1999) 38°F (1971)
May 87°F 64°F 76°F 3.83 in. 100°F (1962) 45°F (1963)
Jun 90°F 70°F 80°F 6.02 in. 101°F (1998) 50°F (1963)
Jul 92°F 72°F 82°F 6.55 in. 101°F (1981) 56°F (1964)
Aug 92°F 72°F 82°F 7.32 in. 103°F (1961) 60°F (1963)
Sep 90°F 71°F 80°F 6.01 in. 98°F (1962) 56°F (1981)
Oct 84°F 65°F 74°F 3.17 in. 97°F (1963) 42°F (1989)
Nov 79°F 57°F 68°F 2.42 in. 92°F (1961) 29°F (1970)
Dec 73°F 50°F 62°F 2.24 in. 90°F (1961) 20°F (1989)
I hope that doesn't get too messed up and you can still see what it says.
Don't worry though - you will have a great trip no matter what! The rain, alot of times, can cool things off if it's later in the day and run lots of others out of the park.
