The Federal Reserve is closed, so most banks will be closed.
They always have the option of being open (Saturdays, for example), but they usually won't post your transactions on that day, since they can't credit/debit their own accounts with the Federal Reserve. In other words, its a non-business day, so everything will post with the date of the next business day, in this case Friday. So they usually don't bother with opening, especially with the availability of ATMs.
So you should check with your individual bank if you need to know, but most likely they will be closed.