The weather over here (I'm in Brooklyn) is fantastic today, blue sky as far as the eye can see. I think it will go ahead.
As an aside, I was at Arthur Ashe Stadium last week for Djokovic and Celic and couldn't believe the size of the place - over 23 000 people and, as far as I could see, pretty much every seat had a fantastic view! I think the Americans do events like these very well, from the singing of the anthem to the upbeat music between games.
I wonder how it would compare to Wimbledon - I've never been.