I have gone in September a couple of times.... It is very hot and very humid, sometimes it almost feels like you walk into a wall of heat (take your breath away hot).. Rains alittle everyday....
But the crowds are very minimal,,, low wait times if any for some major attractions. I love going in September.
I chose the 5th week because we'll be there that whole week, but we're actually arriving on 9/22, so we're really week 4 & 5. I'm so excited, we have so much to celebrate during this trip:
1) Our honeymoon (getting married at home on 9/21)
2) My mom's 50th birthday (10/1)
3) My dad's first trip to WDW (so we're definitely doing MNSSHP!)
4) First time at Food & Wine for all of us
5) First time staying deluxe for DH2B and I ~ Poly & AKL (my Mom, Step-dad & Dad are coming along and are staying at POFQ - I'm VERY lucky in that all of my parents get along very well together!)