The fire weather forecast already exists, it is free, and it is published by the National Weather Service. The problem is not availability. It is that the product was written for fire managers, and it reads like it.
This page is a translation, not a replacement. Where to find yours, what the numbers in it are, and which line tells you something you can act on.
What a Fire Weather Forecast Is For
Ordinary forecasts answer whether you need a coat. This one answers how a fire would behave if there were one — which is a different question, and needs different measurements.
So the fire weather forecast meaning comes down to the audience. It is produced so that incident commanders can decide where to position crews, so land agencies can set restrictions, and so prescribed burns either go ahead or do not. Everything in it is chosen for that purpose: humidity minima, wind at a specific height, and almost nothing about whether it will feel pleasant outside.
Alongside the routine product, offices issue spot forecasts on request: a one-off, site-specific forecast for an active incident or a planned burn. Those are not for general reading, and they are not forecasts for your address.
For the national view, the Storm Prediction Center publishes fire weather outlooks a day or more ahead and grades the risk as elevated, critical or extremely critical. That grading is the closest thing to a scale in the whole system, and it is the fastest way to see whether your region is in a bad stretch.
Fire Weather Zones, and How to Find Your Number
Forecasts are not issued by county. They are issued by fire weather forecast zones, which are subdivisions drawn around terrain, elevation bands and land management boundaries, because fire behaviour follows those rather than political lines.
Each zone has a number, and you will see them written as a state code plus three digits — the form that turns up in searches as zone 214 or zone 117. A county can contain two zones with genuinely different forecasts when one half sits on a valley floor and the other on a ridge.
To find yours, open your local NWS office page on weather.gov and go to its fire weather section. Offices publish a zone map, and the forecast is selectable by zone from there. Make a note of the number once; the zone does not change.
Two things not to confuse it with. A fire weather zone is not an evacuation zone — different authority, different purpose, different map. And it is not a public forecast zone, the unit used for ordinary weather, which is why the boundaries do not match the ones you are used to.
Reading the Text Forecast Line by Line
The text product is a short block of labelled lines, repeated for each day. Most of it is self-explanatory; four lines are not.
Minimum relative humidity. The lowest humidity expected, usually in the afternoon. This is the single most useful figure for a non-specialist: the lower it goes, the more readily fine fuels ignite. Overnight recovery — how far the humidity climbs back after dark — matters too, because a night that stays dry means the fire never slows down.
20-foot wind. Wind speed at twenty feet above the ground, the standard reference height for fire behaviour modelling. It is not the same as the wind in a normal forecast and will often read lower than a gust figure. Direction matters as much as speed.
Haines index. A number from two to six combining the dryness and stability of the lower atmosphere. High values indicate conditions that let a fire grow erratically. It is an index, not a probability.
Mixing height and transport wind. How high the air will mix and how fast it moves up there — which determines where smoke goes and how much a plume can rise. If you follow air quality rather than fire behaviour, this is your line, and Wildfire Smoke covers what to do about it.
Some products also carry a lightning activity level, a one-to-six scale for thunderstorm and ignition potential. Dry lightning on a day with low humidity is the classic way a quiet week becomes a busy one.
When It Becomes a Red Flag Warning
The forecast and the warning are two stages of the same system. The forecast runs every day whether anything is wrong or not. When the forecast values cross the thresholds your local office has set, the office issues a Fire Weather Watch and then, if confidence holds, a Red Flag Warning.
In practice that means the forecast is where you see it coming and the warning is where you act. Everything the warning asks of you — and the reason there is no national threshold — is in Red Flag Warnings. For the household work that should already be done by then, Wildfire Preparedness.
FAQ: Fire Weather Forecasts
What is a fire weather forecast?
A National Weather Service product describing the weather variables that govern fire behaviour — humidity, wind at twenty feet, atmospheric stability, mixing height — issued for fire weather zones rather than counties.
What are fire weather zones?
Forecast areas drawn around terrain and land management boundaries, each with a number. They are smaller and shaped differently from the zones used for ordinary weather forecasts.
How do I find my fire weather zone?
Open your local NWS office page on weather.gov, go to its fire weather section and use the zone map. Note the number, because it does not change.
Where does NOAA publish these forecasts?
Each NWS Weather Forecast Office publishes its own, on weather.gov. The Storm Prediction Center publishes the national fire weather outlook separately.
What is the difference between this and a red flag warning?
The forecast is routine and runs daily. The warning is issued only when forecast conditions cross locally set thresholds. One is information; the other is a call to change what you do.
Sources
- NOAA National Weather Service — Fire Weather Forecast product, fire weather zones and spot forecasts
- NOAA Storm Prediction Center — Fire Weather Outlooks and risk categories
- NWS — Haines index, 20-foot wind and mixing height definitions
- National Wildfire Coordinating Group — fire weather terminology
Zone numbering, product format and publication times are set by each NWS office. This page explains the product; it does not publish forecasts. For current conditions see the Live Emergency Map, and read the forecast itself at weather.gov. When a warning is active, follow local authorities and emergency services before any general guidance. See our Editorial Policy and Sources & Fact-Checking.