All right. Nice guesses all around, people! I agree that this one is a toughie. The correct answer is Cape May warbler. And I believe the bird is a fall adult male.
The first thing you notice about this bird is the striped upper back and the bold white wing bars. Unfortunately the "clincher" field mark of a fall Cape May (the contrasting, lime-colored rump) is not visible. but the bold wing bars and the yellowish wash on the part of the face that's visible are great field marks for a fall adult Cape May. Some fall adult males still show a lot of the rufous in the face—but this one does not.
A Blackburnian warbler in fall does share the Cape May's white wing bars, but the Blackburnian's are bolder. Also a Blackburnian in fall would show pale or white lines (not streaking) along a blacker back.
A black-throated green warbler in fall has an unstreaked upper back.
Blackpoll warbler is another good guess. But I think the larger wing bar is too obvious for a fall blackpoll. And the bird is too yellowish overall, especially in the face.
Below are a few other Cape May warblers in various seasons.