Foliage map / How the forecast works

How our fall foliage forecast works

Every peak date and color status on Leaves.com comes from a model of typical years. Here’s what goes into it, what the viewing score means, and where it can be wrong.

The short version

Fall color moves in a predictable way. It starts in the far north and at high elevation, then works south and downhill over several weeks, arriving last along the coast and the shores of the Great Lakes. The forecast turns that pattern into an expected peak date for any spot in the lower 48, then works out how the color should look on any given day.

What sets the peak date

The model is a phenology model: it uses the long-run relationship between place and the timing of seasonal change. Three things drive fall color timing year after year:

Latitude. Peak arrives about four and a half days earlier for every degree you travel north across the northern states.
Elevation. Color comes earlier as you climb, by roughly four and a half days per 1,000 feet in the East. In the Rockies and Sierra, elevation matters more than latitude, which is why the aspens above 9,000 feet in Colorado turn in late September.
Water. Places near the ocean and the Great Lakes turn a few days later than inland spots at the same latitude, because large bodies of water keep nearby nights milder.

From peak date to today’s color

From each place’s expected peak, the model tracks two things day by day: how much of the canopy has turned, and how many leaves are still on the trees. Early in the season color is building while nearly every leaf is still hanging; after peak the color is there but the branches are thinning. The foliage map recalculates every day, and the date slider lets you look ahead to see color sweep south and downhill through the season.

The viewing score

Each spot gets a viewing score from 0 to 100 that combines color and leaf cover with how much color the region can produce. Forest makeup matters: a sugar maple ridge in Vermont can hit 100, while the Gulf Coast rarely gets past “fair” even at its peak. That’s why two places at the same stage can score very differently.

Elevation for your spot

Elevation shifts timing a lot, so it matters which elevation the forecast uses. Elevations for map taps and most cities are estimated. If you’re headed to a summit, a high pass, or a low river valley, edit the elevation in the report to match where you’ll actually be.

How we checked it

The timing patterns were checked against well-known peak periods in regions like northern New England, the Adirondacks, the Great Smokies, and Colorado’s aspen country.

What the forecast can’t see

The model reflects long-run patterns, not this year’s observations. A warm September, drought, or an early hard freeze can move peak by a week or more, and a windy storm can strip color early. In most years peak lands within about a week of the estimate. For an important trip, check a local report the week before you go. For more on how weather shapes the season, see why leaves change color.

Questions or corrections

If peak in your area reliably runs earlier or later than we show, we’d like to hear about it. Contact us.