Watch vs. Warning: the difference that matters
The National Weather Service issues a Fire Weather Watch when critical fire weather conditions are possible in the next 12 to 72 hours. It means "be aware": the ingredients for dangerous fire behavior are coming together, but they are not certain yet.
A Red Flag Warning means those conditions are happening now or are about to happen, typically within 24 hours. Warm temperatures, very low humidity, and strong winds are expected to combine, so any fire that starts can spread rapidly and behave erratically. A Red Flag Warning is the fire equivalent of "take this seriously right now."
What triggers a Red Flag Warning
Exact criteria vary by NWS forecast office because fuels and terrain differ across the country, but the common recipe is sustained winds (often 15+ mph with higher gusts), relative humidity below roughly 25%, and dry vegetation that can carry fire. Some offices also factor in dry lightning, unstable air, or drought conditions.
Important nuance: a Red Flag Warning does not mean a fire is burning. It means that if one starts, from a power line, a chain dragging on pavement, a lightning strike, or an unattended burn, it will be very hard to stop early.
What you should do during one
Avoid anything that can throw a spark: no outdoor burning, no mowing or trimming dry grass with metal blades, no dragging chains, and no parking hot vehicles over dry vegetation. Many counties impose burn bans automatically during red flag conditions.
If you live in a fire-prone area, treat a Red Flag Warning as a pre-alert: charge your phone, review your evacuation route, and keep an eye on local fire activity. On this site, active Red Flag Warnings appear on the live map and in every location risk report.
Other fire weather products you will see
The NWS also issues High Wind Warnings, Wind Advisories, Heat Advisories, and Excessive Heat Warnings, all of which affect fire behavior. During an active fire, an Extreme Fire Behavior or evacuation-related statement may be relayed through Wireless Emergency Alerts by local authorities.
Fire Nearby ingests all NWS fire, wind, and heat products and links each one back to its official record on weather.gov, so you can always read the source text.
Frequently asked questions
No. It means weather conditions are dangerous enough that any new fire could spread quickly. Check the live map for actual fire activity near you.
Usually a few hours to a couple of days, covering the window when wind and humidity are at their worst. The warning text on weather.gov always lists the exact start and end times.
Official sources
This guide summarizes the following government publications. Read them for full detail.
Keep learning
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