Shade
Method: how SHADE computes shade and felt temperature
Updated on 8 October 2026.
In short
What does SHADE compute?
SHADE (shaderoutes.com) computes the real shade along a route (trees, terrain, buildings) and the felt temperature, in degrees, at each point and at the time you will be there, for running, cycling and hiking.
What is the felt temperature?
Air temperature corrected for altitude (−6.5 °C per 1,000 m), humidity, wind and the sun that really reaches that spot. Formula: Steadman's apparent temperature with net radiation. It deliberately leaves out your own effort.
Why does 40 % shade not mean 40 % of shaded ground?
Shade does not cool equally: under trees the air itself is cooler, while a shaded street still radiates the heat of the tarmac. SHADE weights them: the percentage is felt shade, computed at the height of a 1.80 m person.
How accurate are the split times?
4.6 % median gap with published split times, measured on 5 August 2026 on UTMB and Western States.
Which weather?
Within the next two weeks: forecasts from the national models (ECMWF IFS, DWD ICON, Météo-France AROME and ARPEGE, NOAA GFS) via Open-Meteo. Beyond that: the ten-year normal for the same date (ERA5 reanalysis), never an invented forecast.
Is it free?
Yes, no account required, no ads, no ad tracking.
How the shade is computed
For the chosen time and date, SHADE computes the exact position of the sun at that place, then casts the real shadow of everything that stands up along that bearing.
Trees: canopy density is measured on Sentinel-2 satellite imagery (10 m), and the real height of the trees comes from a global one-metre canopy map calibrated against NASA's space lidar. This is the shade that cools most.
Terrain: shadows cast by the mountains, computed on a real elevation model, which matter at sunrise and sunset.
Buildings: the shadow of each building at its own height, read from the map data. Useful in town, but it cools less.
Water does not count as a cool zone: you cannot run on a lake.
Your speed, and when you get there
You give your average speed on the flat; SHADE derives your pace uphill, downhill and by terrain to know when you will be where. The model rests on the metabolic cost of running on a gradient (Minetti), Tobler's hiking function and a power balance for cycling.
Race mode
You give the time you are aiming for. SHADE spreads it over the checkpoints from the race's real profile, read every hundred metres, and a metabolic cost model, with an ultra's loss of pace fitted on genuinely recorded split times.
The result was checked against published UTMB and Western States split times: 4.6 % median gap (measured on 5 August 2026).
A race is only published with a real course from the organisers, and the page says which edition it comes from.
The data
Mapping and routing: OpenStreetMap contributors (ODbL). Tree cover: Sentinel-2 cloudless (EOX, CC BY 4.0) from ESA Copernicus Sentinel-2 imagery. Elevation: AWS Terrain Tiles. Weather: Open-Meteo (national model forecasts, ECMWF ERA5 / ERA5-Land reanalysis).
Limits
This is an estimate, not a guarantee: the map may miss a path or a tree, and the real weather and ground may differ.
City loops are generated automatically: always check that a route is safe and accessible before you set off.
The felt temperature describes the place, not your body: it does not replace a doctor's advice or the race organisation's instructions.