Strong winds may cause birds to get blown off-course, ending up some place they did not intend to go. But most birds recover after the storm, with their internal GPS device getting them to where they intended to go.
Birding in early to mid-May can be good even though many migrants do not venture this far east, preferring a more direct path northward bypassing the Cape and Islands.
There are behavioral observations that can help us confirm breeding status; my favorite ones are observing a bird carrying vegetation or carrying food.