What Is the Burn Score and How Does It Work?
BurnAtlas condenses up to nine weather factors into a single 0–100 Burn Score. Here is what goes into it, what the ranges mean, and how to use it without switching off your own judgment.
The Burn Score is a 0–100 rating that summarizes how favorable current and forecast conditions are for a controlled burn. It exists to answer one question quickly — is this a promising day to look at more closely? — while still exposing the underlying factors so you can make the final call.
What goes into the score
The score is built from professional prescribed-fire weather factors. Depending on what data is available for your location, it runs in one of two modes.
Basic mode (4 factors)
When only standard weather data is available, the score is based on:
- Wind speed — ideal is a light, steady breeze (roughly 2–6 mph at eye level).
- Relative humidity — ideal is around 30–50%.
- Precipitation probability — lower is better for carrying a burn, ideally under 10%.
- Temperature — moderate temperatures (about 60–85°F) are easiest to manage.
Enhanced mode (up to 9 factors)
Where the National Weather Service publishes fire weather data — most common in the Western US and fire-prone regions — the score adds several professional factors:
- 20-foot wind and transport wind for spread and smoke transport.
- Mixing height, a critical safety factor for smoke lift.
- Atmospheric dispersion index for how well smoke will clear.
- Fine fuel moisture, estimated from temperature and humidity.
The algorithm automatically detects which mode applies, so you always get the most complete picture your location supports.
How to read the number
Higher is better, but the score is a starting point, not a verdict:
- High scores indicate that most factors fall within professional prescription ranges at the same time — a window worth examining.
- Middling scores usually mean one or two factors are marginal. Open the breakdown to see which.
- Low scores flag conditions that are too windy, too dry, too wet, or too stagnant for a safe, controllable burn.
The score is conservative by design: it applies steep penalties to genuinely unsafe conditions, like a critically low mixing height, so a single dangerous factor can pull down an otherwise good-looking day.
Use it — but keep your judgment
A strong Burn Score never replaces a written burn plan, local regulations, a check for active burn bans, or your own on-site assessment. Think of it as a fast filter that helps you find candidate days and understand why conditions are or are not favorable — then verify everything on the ground before you ignite.
The Burn Score is a planning aid aligned with prescribed-fire training standards. It does not authorize any burn or guarantee safety.