When Dr. Rachel Dubroff and her family chose their apartment at Riverside Boulevard and 63rd Street in Manhattan, they were thrilled by its picturesque views of the Hudson River. But they did not expect to have a front-row seat to an annual whale-watching event.

For two years in a row, Dr. Dubroff said on Tuesday, she has spotted a whale swimming outside her living room window. Last year, she didn’t quite believe the sighting was real. But she saw a whale again on Saturday — and in the same spot again on Sunday — and news reports confirmed her hunch: The Hudson River has a resident humpback.

“It was general excitement and shock,” Dr. Dubroff, 39, said, “and how thrilling that a whale can be in the Hudson, based on what we see float by sometimes.”