The best source of information on the population status of Cape May Warbler is the Breeding Bird Survey (BBS), although its reliability is only medium because the northern extent of the breeding range is not well covered. BBS data indicate a strong increase from the 1970s through the mid-1980s, a decline back to mid-1970s levels by around 2010, and then another period of rapid growth, with the population currently at record high levels, more than triple the size of the early 1970s. This fluctuation largely reflects patters of Spruce Budworm abundance. At a regional level, numbers within southern Ontario and Quebec and the southern boreal forest are consistent with the increases seen at the national level, while little change has been observed in the Maritimes.

The goal for Cape May Warbler is to remain at or above its recent population level, based on the Breeding Bird Survey. Trend data show that Cape May Warbler is currently within its goal range.