So I'm trying to decide whether or not to get my BMs Pashminas as part of their gift... but is it necessary for September?  (Labor Day...)

ugh, that's what sucks about Ohio...you never know! USUALLY it's pretty nice over Labor Day, but it could be a little chilly by then. Tough call :(

you can search online for weather temperature & precipitation records over the years. I'm getting married the same time & I thought I remembered it being warm/mild the past couple years with little to no rain. I forgot the website, I'd have to do some searching

typically, in September its still kinda warm. It doesnt get cold until mid October

Agree with Amanda! September can be  non stop raining one day and the next day hot as a August day. Usually around Halloween when it typically starts dropping low in temps and remain there.