About Autumn Guide

There are foliage trackers across the globe, but none of them bring the world together. Autumn Guide's goal is to celebrate, nurture, and help people around the world learn about the season that takes over twice a year.

How the model works

Using daily temperatures from the ERA5 weather reanalysis (via Open-Meteo), we run a phenology model that weighs day length against autumn temperatures to calculate when the leaves turn, and an early hard frost can still yank the peak forward on its own. Elevation matters too: each cell shifts timing by about a day for every 300 meters of altitude. Prior seasons use real observed data, and that record helps guide the forecast. Slide the slider on the tracker and watch fall colors move.

Verified against the real world

Weather doesn't tell the whole story. Seattle and Duluth sit at nearly the same latitude with near-identical September weather on paper, yet Duluth's birches and aspens turn three weeks before Seattle's maples do. So every region also gets checked against published peak dates and adjusted by hand, which lets us score places the model was never built for in the first place. Click any spot on the map to see the exact position. If you notice something off, don't hesitate to get in touch at hello@autumnguide.com.

Data & thanks

Weather data by Open-Meteo.com (CC BY 4.0), built on ERA5 from the Copernicus Climate Change Service. Base maps by OpenFreeMap and OpenStreetMap contributors. Elevation from Mapzen/USGS terrain tiles. Region boundaries derived from Natural Earth (public domain). Thank you to these projects for helping support our modeling.