They probably could not postpone it, if the production people for fireworks and sound and lights had commitments after the fourth.
Preponing it may have been the best solution to having the event at all.
And it still may get rained out.
this should not bother you. What would bother me is if they cancelled entirely- this shows that at least the libs care about contracts and possibly the Fourth.
What you say is true.Also, the stage is enclosed in a half
shell,which makes it open to the elements.