What is a red flag warning?

A National Weather Service warning that conditions are ripe for fire: wind, low humidity, dry fuels, and often lightning.

Forecasters issue red flag warnings when weather and fuels line up: strong wind, low relative humidity, unstable air, or lightning over country dry enough to take it. Critical fire weather is the broader term for the same family of conditions.

Lightning over receptive fuels deserves special attention: it can seed dozens of starts in an afternoon, across country too big to patrol.

For contractors

Fire weather is a demand forecast. A red-flag day over dry fuels is tomorrow’s fire list forming; a week of them is a regional commitment building. Check the zones against where your equipment sits.

In the briefing

The briefing carries a daily lightning fire risk read, ranked LOW to EXTREME. When risk runs high, the weather section moves to the top: the placement is the signal.

Related terms

Preparedness Level · Initial attack

The briefing puts these signals in your inbox by 8:30 AM Mountain, free. Get the morning briefing