Some waterfront homes are a safer bet than others. Consider the five-bedroom home of Richard and Kim Alexander in Rowayton, a coastal village in Norwalk, Conn. After the 3,500-square-foot property sustained water damage in Hurricane Irene in 2011 and Hurricane Sandy in 2012, the Alexanders spent roughly $300,000 to raise the house and the grade of the lot, exceeding FEMA elevation standards. “As soon as I saw the damage from Sandy, I basically said to myself, ‘Third time is not a charm,’” said Mr. Alexander, 57, a consultant. “We’ve got to mitigate this flood exposure.”

The house is currently listed for $1.75 million. Amanda Davenport, the listing agent, said that elevating the property added $250,000 to the list price and helped attract nervous shoppers. “Nine out of 10 buyers will say, ‘I’m only looking at houses that are FEMA-compliant,’” said Ms. Davenport, a saleswoman for Halstead Property. “And that’s different from two weeks ago.”

A buyer made an offer on the house as Hurricane Irma was pummeling Florida, and the offer was accepted.

KNOW YOUR RISKS AND MAKE A PLAN

To protect yourself and your family from the unknown, you need to have some idea of what that unknown might be. If you live in New York, for example, you should prepare for blizzards, hurricanes and extreme heat, but you probably don’t need to spend too much time fretting about earthquakes.

Not all risks, however, are immediately obvious. The Federal Alliance for Safe Homes has a map that lists peril risk by state. Once you know your risks, download the Know Your Plan app from the Insurance Information Institute, which provides detailed checklists to help you prepare for various emergency scenarios.

At the very least, families should keep an emergency kit on hand. What you store in that kit will depend on where you live and the potential hazards you face. Generally, you’ll be dealing with one of two scenarios: the need to evacuate or to shelter in place. To make a speedy exit a smooth one, pack a backpack full of supplies for each family member. To stay put safely, you’ll need enough provisions to sustain your household for at least 72 hours.