Flash floods: What they are and how to stay safe

By Allstate

Last updated: November 2021

Flash floods can be dangerous because they happen quickly and can be unpredictable, says the National Severe Storms Laboratory (NSSL). If a flash flood strikes in your area, it's important to know what you can do to help keep you and your family safe. Here are some tips to help you prepare and stay safe during a flash flood:

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What is a flash flood?

Flash floods are sudden, fast-moving floods that typically occur within three to six hours of heavy rainfall, says the National Weather Service (NWS). A flash flood can also result from a dam breach or mudflow. It's important to remember that since it can rain anywhere, everyone is at risk for flash flooding. However, you may be at a higher risk for flash floods if you live near a dam or in an urban area, says the NWS.

General flash flood safety tips

Because flash floods can happen with little warning, it may be helpful to prepare during dry times. Consider developing an evacuation plan and create an emergency "go bag" so that you're ready to evacuate quickly if a flash flood threatens your area. You should also be sure that you and your family understand the difference between a flash flood watch and warning. The NSSL explains that a flash flood watch means flooding is possible, while a flash flood warning is issued when flooding is about to occur or already happening.

Lastly, you can prepare for a flood by purchasing a flood insurance policy. Flood insurance can help pay for repairs to your home or belongings if they're damaged by a flood. Keep in mind that there may be a 30-day waiting period for your policy to go into effect.

How to stay safe at home during a flood

If you're at home when a flash flood strikes, the NWS offers these tips to help you stay safe:

  • Follow evacuation orders: If local officials have provided evacuation instructions before or during a flash flood, it's important to take them seriously as the timing of these floods can be unpredictable.
  • Move to higher ground immediately: If your home floods, get to higher ground as soon as possible. However, you should avoid seeking shelter in a closed attic as you may risk becoming trapped by rising floodwater. Only get on the roof if necessary and signal for help once you're there.
  • Avoid contact with floodwater: Try to avoid contact with floodwater that enters your home. Avoid rooms, including the basement, where floodwater has touched or submerged electrical outlets or cords. This is because you may be at risk for electrical shock.

How to stay safe in a car during a flood

If you're in the car and a flash flood is imminent or occurring, try to stay calm and remember these tips from Ready.gov:

  • Don't drive around barricades: If you come across a barrier blocking a flooded road, do not drive around it. Instead, back up and find an alternate route.
  • Avoid driving on bridges over fast-moving water: Floodwater can wash out a bridge with little or no warning. If water is moving quickly under a bridge, avoid driving over the bridge.
  • Avoid driving through floodwater: Driving through floodwater is dangerous, as it only takes 12 inches of water to for a small sedan or SUV to float, says the NWS. You should also avoid driving through large puddles. They may look more shallow than they are, and can disguise hazards such as a washed-out road or sharp debris.
  • Stay in your vehicle if you're surrounded by fast-moving water: Unless water is rising inside your vehicle, do not exit the vehicle when you're surrounding by quickly-moving floodwater. If water is rising inside your vehicle, exit the car and get onto the roof.

If you're ever in doubt about you or your family's safety during a flood, remember to turn around, don't drown, says the NWS.

Flash floods can happen suddenly and without warning. By planning ahead and remembering these flood safety tips, you and your family can be better prepared if a flash flood affects your area.