Elevation sets the order in Arizona.
Aspen on the San Francisco Peaks above Flagstaff, at Lockett Meadow and the Snowbowl, turns in the first days of October, with the White Mountains and the Kaibab Plateau close behind.
The change then steps down the Mogollon Rim into the canyons, where cottonwood and sycamore along Oak Creek and the Verde River turn gold through the last days of October.
From the peaks to the creek bottoms the spread is close to a month.
In a typical yearWednesday, Mmmmmmmmm 30 (latest map)
Bordering states
Color: Fallcast, the same map as the app. Basemap © OpenStreetMap contributors, Protomaps. Place outlines: U.S. Census Bureau.