Red flag warning: what it means and what to do
When critical fire weather conditions are happening or forecast, the local National Weather Service office issues a Red Flag Warning: dry fuels, low relative humidity, and strong wind, sometimes dry lightning. The exact thresholds are set by each local office, so they vary by region. For example, the Los Angeles/Oxnard office warns when relative humidity is 15 percent or less with wind gusts of 35 mph or more for at least 6 hours.
Right now4Red flag warnings in effectas of Every term in the storm glossary
Watch vs warning
| Product | What it means | Lead time | What to do |
|---|---|---|---|
| Red Flag Warning | Critical fire weather is occurring or imminent; any fire can spread quickly. | Usually issued within 48 hours when confidence is high. | No outdoor burning, park off dry grass, secure chains, be ready to evacuate. |
| Fire Weather Watch | Critical fire weather hasn't arrived yet, but it's still possible. | Issued 18 to 96 hours ahead. | Stay informed and start preparing; don't wait until a warning is issued. |
What the criteria look like
| Location | Humidity | Wind | Other |
|---|---|---|---|
| Los Angeles/Oxnard | 15 percent or less | Winds blow steadily at 25 mph or more, or frequent gusts hit 35 mph or more. | Conditions last 6 hours or more |
| New York | Under 30 percent | Sustained or gusting above 25 mph | Rainfall in the prior 3 days came to under 1/4 inch. |
| General guideline | 25 percent or less | Sustained 15 mph or more | After a dry spell, temperatures top 75 F. |
Staying safe during a red flag warning
- No outdoor burning or open flames.
- Don't park on dry grass.
- Secure trailer chains so they don't drag.
- No fireworks.
- Have an evacuation plan and know your zone.