Canada warbler by Cris Hamilton. Olive-sided flycatcher, ruby-throated hummingbird, eastern wood-pewee from Wikimedia Commons
31 August 2025
This week I discovered a BirdCast blog from 31 July that lists Peak Fall Migration Windows for 1000 US Cities. The date ranges are “seasonal windows during which 50% of total nocturnal bird migration traffic historically passes through each city based on radar measurements from the last two and a half decades.” This peak is not just warblers. It’s bird bodies passing overhead including thrushes, blackbirds and sparrows.
Of course I looked up Pittsburgh. Our peak is 9/15/2025 through 10/11/2025.
What about everywhere else? Looking up each city was frustrating. I wanted a beautifully shaded map like the one BirdCast put out for spring migration at The picture is worth three billion birds: peak migration timing for the contiguous US, thumbnail below.
But no such map exists for fall migration so I mapped it myself using peak start dates on a city lights satellite map. After all, most birds are migrating at night. Once peak migration starts it lasts 3 to 4.5 weeks.
My colors are Yellow–>Orange = August, Green–>Blue = September, Purple = October.
Peak Fall Migration Start Dates in U.S. Cities
As you can see peak fall migration times are all over the map, sometimes the reverse of our north-to-south expectations.
The first peaks are in Arizona, New Mexico, Colorado and Wyoming in the second half of August (yellow is earlier than orange on the map above). Weirdly the peak in Phoenix (yellow) is earlier than the peak in Denver (orange).
Pacific coast migration looks normal from Seattle to San Francisco but Los Angeles has its peak *before* those northern cities.
In Texas, Houston peaks two weeks before Dallas. Hmmm.
Migration looks like a rolling wave north to south as expected (green-to-dark-blue) in the area from the Mississippi to the Appalachians.
But the East Coast from Massachusetts to Virginia Beach peaks in early *October*!
Maybe that’s why BirdCast did not create a map.
Meanwhile Pittsburgh is not at peak migration yet but the species pictured above are at their own peak in our region: Canada warbler, olive-sided flycatcher, eastern wood-pewee and ruby-throated hummingbird. To find the peaks by species see The Return of Migration Tools at BirdCast.
It’s a good time to get outdoors!