The Canadian population of Western Flycatcher is best monitored by the Breeding Bird Survey (BBS), which has high precision and fairly good coverage of the breeding range, although northern parts are sampled less. The national trend shows periodic fluctuations, but overall an increase from the early 1970s to mid-1990s, a decline back to around late 1980s levels by 2005, and then a slight increase again until another downturn began in 2020. Overall there has been a large increase of 138% relative to the early 1970s. Trends differ regionally, with a large long-term increase along the Pacific Coast, compared to a slight decrease in the interior of British Columbia and more moderate increases in the Rockies.

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