Flash Flood Warning: What to Do Immediately
A Flash Flood Warning means dangerous rapid flooding is occurring or imminent in the warned area; move away from low ground, never enter floodwater on foot or in a vehicle, and follow current National Weather Service and local emergency instructions.
Timeline
- Warning received: Check whether you are inside the warned area and act immediately on location-specific instructions.
- Move up: Leave low spots, channels, underpasses and flood-prone roads for higher ground without crossing water.
- Stay informed: Monitor official alerts and remain away from flooded areas until authorities say conditions are safe.
A Flash Flood Warning means rapid, dangerous flooding is occurring or expected soon in the specified area. It is a call to act, while a Flood Watch means conditions are favorable and people should prepare and monitor updates. Read the warning polygon and text, because a county-wide alert may describe a more specific corridor, stream, burn scar or urban area. Follow any evacuation or shelter instruction from local officials immediately. [1][2][3]
If you are in a vulnerable low area, move to higher ground without crossing floodwater. Leave creek beds, drainage channels, underpasses, dips and other places where water collects. Flash flooding can begin within minutes and can occur downstream from rain that fell elsewhere. At night, depth, current and washed-out pavement are even harder to see. Keep receiving alerts because the threatened location and safest route can change. [1][2][4]
Do not drive through a flooded road or around a barricade. Water can hide a missing road surface, debris, a strong cross-current or a deeper channel than the visible edge suggests. The National Weather Service warns that about 12 inches of moving water can float a small car, while deeper water can carry away larger vehicles. Turning around is safer than trying to estimate depth or assuming a heavy vehicle can maintain traction. [1][3][5]
Do not walk or swim through floodwater. Fast-moving water around six inches deep can knock an adult off balance, and the flow may contain sharp debris, sewage, chemicals or live electrical hazards. Keep children and pets away from drains, streams and flooded streets. A familiar crossing is not safe simply because it was passable during a previous storm; erosion and current speed can change beneath opaque water. [1][3][5]
If water is rising around a building, follow emergency instructions and move to a higher level when that is the safer available option. Avoid a closed attic unless there is a way to reach the roof, because rising water can trap occupants. If trapped, call emergency services and signal your location. If a vehicle is surrounded by quickly rising water, use current official guidance and leave for higher ground only when it can be done safely. [3][5][6]
Special settings require earlier judgment. Canyons, normally dry washes, wildfire burn scars and urban pavement can produce fast runoff with limited local rainfall. Campers and hikers should identify escape routes before storms, while drivers should know alternate routes that avoid low-water crossings. Never stop on a bridge to watch flooding, and do not enter a restricted area to photograph or report conditions; observations are useful only when made from safety. [1][2][4]
After water recedes, continue to obey closures and official instructions. Roads and bridges may remain undermined, floodwater may be contaminated, and downed electrical lines can energize wet ground. Use National Weather Service alerts and local emergency management for current conditions. This guide cannot determine the safest action for every building or route; during an active warning, location-specific official directions take priority over general advice. [3][5][6]
Sources
- National Weather Service — Flooding Safety
- National Weather Service — Basic Flash Flood Safety Rules
- National Weather Service — During a Flood
- National Weather Service — Floods and Flash Floods
- NOAA National Weather Service — Flood Safety
- CDC — Safety Guidelines: Floodwater