This evening while out kayaking I surprised an out-of-season Least Bittern in the North Bay (1st Bay; near the Hudson-Greenport line).
I had a good, quick look at its head and upper plumage. The buff wing patches were prominent as it took wing into the cattails a few feet away.
Due to the extent of its buff, brown and generally streaked appearance, I'd normally say (in summer) that it was a juvenile.
Bull (1974) gives October 17 as the extreme inland date, with November 19 listed as the late date for the coast. A few midwinter records are all coastal except for one at Iona Island, from February 3 to March 3, 1952 (Orth).
I'd imagine those dates and records have been surpassed by now.