Currently Explains: Flash Flood Safety

Flash flooding contributes to roughly 90 deaths and $10 billion in property damage a year in the United States.

They occur suddenly — usually within a few hours of heavy rainfall — when a body of water becomes inundated and oversaturated, causing an overflow and surge of water that has the potential to be devastating to its surroundings with its power and force.

“Areas prone to flash flooding include streams, creeks, rivers and other waterways, normally dry stream beds, urban areas, areas of poor drainage and saturated or impervious land surfaces,” says Currently’s Chief Meteorologist, Megan Montero. 

“You can also find flash flooding in steep terrain where you see concentrated runoff, burn scars from wildfires, areas where surface vegetation is removed, or even where excess runoff from  warm rainfall falls on significant snowpack.”

Most recently, Hurricane Fiona made landfall in Puerto Rico, leaving the entire island without power and causing widespread flooding and mudslides.

Roads, bridges and other infrastructure have already suffered and crumbled under the weight of the extreme rains, island officials say. 

The storm comes just 5 years after the anniversary of Hurricane Maria — a category 4 storm that took the lives of nearly 4,000 Puerto Ricans and left tens of thousands more without power or basic necessities in the aftermath of the storm.

And the severe weather conditions are only expected to increase. The storm is expected to make a historic landfall in Canada on Friday.

What else do you need to know?

As global temperatures continue to rise due to climate change, the threat of flash flooding becomes imminent, regardless of geographic region.

A warming atmosphere means more precipitation in the air that must be released as either rain or snow, increasing the likelihood of flooding everywhere by 25 percent over the next few decades.

“We will see an increasing threat of flash flooding the next decades due to increasing global temperature. As global temperatures increase, that will mean the atmosphere can carry more moisture. More moisture means more rainfall and the potential for increased moderate to intense rainfall for most areas,” said Montero.

Those who live in the southern and eastern coastal communities of the country will feel the impacts of these changes most deeply, researchers say. It’s worth noting that Black and Brown communities make up the majority of these flooding pathways, meaning that they will be disproportionately impacted by extreme weather in coming decades.

What should I do?

The best way to prepare for any extreme weather event, is to become well-versed in the conditions of your immediate environment.

Some questions worth considering include:

  1. Do I live in a flood prone area?
  2. Where is the nearest water source to me?
  3. When was the last major flooding event in my area?
  4. Am I aware of where the closest evacuation zone might be?
  5. Do I have, or need, flood insurance?

Next, now that you’ve adequately assessed your community and its vulnerability risk, you can now make the necessary arrangements to make your life more flood-resilient.

A Flash Flood Checklist:

Before a flood:

  • Risk Assessment
  • Insurance
  • Emergency Plan


  • Execute Emergency Plan
  • Evacuate if necessary
  • Listen to the radio, follow the weather forecast


  • Avoid driving
  • Wear protective clothing
  • Stay away from exposed wires, potential electrocution
  • Avoid wading in dangerous waters

Nearly half of all flash flood-related deaths in the U.S. involve automotive vehicles

If you live in an area that is prone to regular flooding, make sure to regularly check a trusted weather source for daily flood or flash flood watches — this will help you make the safest decisions for you and your car.

Should you find yourself in or around a car at the time of a flash flood, avoid large bodies or puddles of water and opt for higher ground, even if it means abandoning your vehicle and moving by foot. Just six inches of water is enough to stall most cars.

What to do if you are trapped inside your car during a flash flood:

  1. Stay calm.
  2. Unfasten your seatbelt.
  3. Open or break any windows, and climb out.
  4. In the worst case scenario, wait for your vehicle to fully submerge under water, then unlock any doors, escape and swim to safety.

Once you’ve located a safe place, wait and listen for local authorities to tell you it’s safe to return to your home.


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