DH, DS and I were at WDW July 2002 (I've gone in July 3 times total, you WILL have a great time). It rained 3 times in 5 days while we were there on that trip, BUT one night it was raining just before Illuminations was suppose to start. It was pouring and there was a little lightening, so 75% or more of the crowds left! And of course, as can be expected in the rainy season, the rain let up in about 20 minutes, just in time for us to enjoy a wonderful, unobstructed view of Illuminations! The summer storms usually come up quick and leave just as quick as they came. Put on a poncho and have fun! Just be careful of the lightening. My brother lives in Miami and my Dad lives in Bonita Beach and everytime I go for a visit I hear of someone getting struck by lightening. Go inside if there is lightening.
Lori