We've been in May several times. Usually the week prior to Memorial Day weekend..actually departing Disney on the Saturday of Memorial Day weekend. I guess we've been lucky, because I've found the weather to be very nice. Warm, without the humidity that we were accustom to during our August visits. The parks weren't all the crowded and we were able to obtain advance dining reservations quite easily. It does appear to get more crowded as the Memorial Day weekend approaches, but we area usually leaving by then, so it wasn't an issue.