What to Do During a
Flash Flood Warning
Flash flooding is the #1 weather-related killer in the United States. A flash flood warning means it's happening now or about to happen. Here's what you need to know.
Flash Flood Warning vs. Watch vs. Advisory
Flash Flood Watch
Conditions are favorable for flash flooding. Heavy rain is expected. Be ready to move to higher ground if needed. Stay aware.
Flash Flood Warning
Flash flooding is imminent or already occurring. This is an emergency. Move to higher ground immediately if you're in the affected area. Do not wait.
Flood Advisory
Minor flooding is occurring or expected. Nuisance-level — ponding on roads, small stream overflow. Not life-threatening but use caution.
What to Do Immediately
Move to Higher Ground
Don't wait to see the water. Flash floods arrive in minutes, not hours. If you're near a creek, river, or low-lying area, move uphill now.
Never Drive Through Floodwater
"Turn around, don't drown." Six inches of moving water can knock you down. Twelve inches can carry away a car. You cannot tell how deep water on a road is.
If Trapped in a Building
Move to the highest floor. Do not go into the attic unless you have roof access — people have drowned in attics. Call 911 and signal from a window.
Stay Informed
Keep monitoring alerts. Flash flood warnings are updated frequently. The NWS will issue an all-clear when the threat passes. Don't return to flooded areas until officials say it's safe.
Why Flash Floods Are So Dangerous
Unlike river flooding that rises over hours or days, flash floods happen in minutes. A dry creek bed can become a raging torrent in the time it takes to eat dinner. They're most common in:
- Mountain hollows and narrow valleys — water funnels downhill fast with nowhere to spread
- Urban areas — concrete and asphalt don't absorb rain, so water runs off immediately
- Burn scar areas — land scorched by wildfire repels water, causing extreme runoff
- Low-water crossings — roads that dip through creek beds are death traps during flash floods
Most flash flood deaths in the US are people in vehicles who drove into floodwater.
After the Warning Expires
Don't assume it's safe just because the warning ended. Floodwater can linger for hours. Roads may be washed out underneath. Bridges may be structurally damaged. Let first responders clear routes before you try to drive through a previously flooded area.
If you have a USGS river gauge near you, check whether levels are still elevated. A river can stay above flood stage long after the rain stops.
Get Flash Flood Warnings on Your Phone
StormCast pushes NWS flash flood warnings to your Android phone within seconds of being issued. You can also monitor USGS river gauges in your area and get alerts when water levels rise into flood categories.
Download StormCast Free on Google Play