As I replied to you earlier this is one meet I almost definitely could go to I've been to Niagara Falls seven times in the past three years.

I normally go there in January. However, it's VERY cold then and the roads and sidewalks are very slippery. I have a lot of fun slipping and sliding in my car, but some don't enjoy that kind of thing.

September would probably still be pretty decent weather. Anything after that it starts getting pretty cold very quickly.