The 20 Most Vulnerable Cities to Flooding in the United States

From heavy rain and flash floods to hurricanes and storm surges, flooding is the most common natural disaster in the United States.

Not only does flooding put over 40 million Americans at risk each year, but it also is incredibly costly. It incurs approximately $20 billion worth of damage to at-risk homes each year, not to mention the additional cost of damage to public property and infrastructure. Rising sea levels and more frequent extreme weather caused by climate change are projected to worsen flooding in the United States with each passing year.

Unfortunately, homeowners are among the hardest hit by flooding. Insurance costs are higher for homeowners in flood zones; in addition to the cost of standard home insurance, flood insurance can add another $900 or more per year. And in the event that a home is flooded, home insurance premiums typically rise. On top of this, a home that sustains water damage tends to decrease significantly in value even after renovations, selling for between 10-20 percent less. 

A city’s preparedness and its resources to combat flooding can go a long way. Yet, flooding events — from minor, moderate to major — leave communities floundering in their wake each year. With flood risk on the rise across the United States due to climate change, flood vulnerability looms large as an increasingly costly issue.  

To identify the most vulnerable cities to flooding in 2021, researchers at Insurify analyzed environmental and sociological data published by the University of Notre Dame. They assigned each of the United States’ major metropolitan areas a Flood Vulnerability Score based on a combination of factors, from flood probability to social, economic, and governmental preparedness.

Insights

• National averages. Across the 280 major metropolitan areas in the United States, the average Flood Vulnerability Score is 38.5 out of 100. Among the top 20 most at-risk cities, the average score is almost exactly twice as high, at 77.1 out of 100. According to the most recent data from Realtor.com, the average home sale price in the United States is approximately $365,817, while the average time a home spends on the market is 56 days.
• Southern and Southwestern clusters. Notably, none of the most vulnerable cities to flooding are located in the northern half of the United States. Among the cities located on the coast, rising sea levels caused by warming oceans and melting glaciers increase the likelihood of coastal flooding each year. Inland, cities in arid climates are at risk of flash floods caused by heavy rain (which is intensified by climate change), while overflowing rivers and reservoirs are the main contributors of flooding in cities such as Sacramento and San Jose. 
• High flood risk, high demand? Despite having the highest risk of flooding in the nation, the real estate market in nearly all of the twenty most vulnerable cities is healthier than average this year. While it is true that the real estate market across the country is booming in 2021, housing markets are hotter than average among the twenty cities on this list. In fact, houses in these top 20 cities are selling for more than one and a half times the national average and lasting less than two-thirds the average time on the market before being sold. Specifically, the average home listing price among these top twenty cities is $613,999, which is 68 percent higher than the national average, while the average house is on the market only 35 days before being sold, 38 percent below the national average. 

Methodology

The data science team at Insurify, a website to compare homeowners insurance, referred to data from the University of Notre Dame’s Urban Adaptation Assessment to determine the most vulnerable cities to flooding in 2021. Data on the probability of a major flood within the next two decades (before 2040), the proportion of the population and critical infrastructure exposed to the flooding hazard, as well as the economic, social, and governance measures in place to combat it were gathered from the University of Notre Dame’s Adaptation Assessment. These statistics were used to create a composite score quantifying each city’s relative vulnerability to flooding. Composite scores were then normalized to a 0-100 scale, with a higher score indicative of a higher probability of flooding, higher sensitivity, and lower levels of preparedness. The 20 cities with the highest scores were identified as the most vulnerable in the nation to flooding.

Real estate statistics by city (median listing price and time on market) were gathered from Realtor.com. In order to account for month-to-month fluctuations in these statistics, Insurify’s data scientists took the average of their most recent three months for each city.

The cost of flooding to homeowners in the United States was gathered from the First Street Foundation’s Flood Factor report.

Which city is the most vulnerable to flooding, 2021?

Saint Petersburg, Florida is the most vulnerable to flooding compared to all other metro areas in the United States, with a Flood Risk Score of 100 out of 100. This designation is based on a statistical analysis of climatological and sociological data.

These 20 Cities are the Most Vulnerable to Flooding in the United States

20. Surprise, Arizona 

• Flood Vulnerability Score: 65.6 out of 100
• Median home listing price: $426,237 (17% above the national average)
• Median days on market: 26 (54% below the national average)

19. San Diego, California

• Flood Vulnerability Score: 67.1 out of 100
• Median home listing price: $871,482 (138% above the national average)
• Median days on market: 62 (10% above the national average)

18. Roseville, California 

• Flood Vulnerability Score: 67.8 out of 100
• Median home listing price: $589,489 (61% above the national average)
• Median days on market: 19 (66% below the national average)

17. Orlando, Florida

• Flood Vulnerability Score: 67.9 out of 100
• Median home listing price: $327,650, (10% below the national average)
• Median days on market: 51 (8% below the national average)

16. Antioch, California

• Flood Vulnerability Score: 69.7 out of 100
• Median home listing price: $517,975 (42% above the national average)
• Median days on market: 18 (68% below the national average)

15. Stockton, California

• Flood Vulnerability Score: 70.8 out of 100
• Median home listing price: $484,416 (32% above the national average)
• Median days on market: 20 (64% below the national average)

14. Sacramento, California

• Flood Vulnerability Score: 72.5 out of 100
• Median home listing price: $589,489 (61% above the national average)
• Median days on market: 19 (66% below the national average)

13. Concord, California 

• Flood Vulnerability Score: 73.1 out of 100
• Median home listing price: $736750 (101% above the national average)
• Median days on market: 19 (67% below the national average)

12. Hayward, California

• Flood Vulnerability Score: 73.5 out of 100
• Median home listing price: $1,043,815 (185% above the national average)
• Median days on market: 24 (57% below the national average)

11. Corpus Christi, Texas

• Flood Vulnerability Score: 74.3 out of 100
• Median home listing price: $299,830 (18% below the national average)
• Median days on market: 62 (12% above the national average)

10. Clearwater, Florida

• Flood Vulnerability Score: 74.7 out of 100
• Median home listing price: $319,150 (13% below the national average)
• Median days on market: 34 (38% below the national average)

9. San Jose, California

• Flood Vulnerability Score: 75.0 out of 100
• Median home listing price: $1,236,300 (238% above the national average)
• Median days on market: 18 (68% below the national average)

8. Fairfield, California

• Flood Vulnerability Score: 78.2 out of 100
• Median home listing price: $534,899 (46% above the national average)
• Median days on market: 13 (76% below the national average)

7. Midland, Texas

• Flood Vulnerability Score: 79.9 out of 100
• Median home listing price: $321,317 (12% below the national average) 
• Median days on market: 53 (6% below the national average)

6. Cape Coral, Florida 

• Flood Vulnerability Score: 80.2 out of 100
• Median home listing price: $365,554 (at the national average) 
• Median days on market: 45 (19% below the national average)

5. Modesto, California

• Flood Vulnerability Score: 84.3 out of 100
• Median home listing price: $478,050 (31% above the national average)
• Median days on market: 24 (57% below the national average)

4. Salinas, California

• Flood Vulnerability Score: 86.4 out of 100
• Median home listing price: $1,298,833 (255% above the national average
• Median days on market: 46 (17% below the national average)

3. Brownsville, Texas

• Flood Vulnerability Score: 86.6 out of 100
• Median home listing price: $283,300 (23% below the national average) 
• Median days on market: 91 (63% above the national average)

2. Santa Clara, California 

• Flood Vulnerability Score: 93.4 out of 100
• Median home listing price: $1,236,300 (238% above the national average)
• Median days on market: 18 (68% below the national average)

1. Saint Petersburg, Florida

• Flood Vulnerability Score: 100 out of 100
• Median home listing price: $319,150 (13% below the national average)
• Median days on market: 34 (38% below the national average)

If you have any questions or comments about this article or would like to request the data, please contact insights@insurify.com.

Insurify Insights

Insurify’s team of data scientists and content specialists presents Insurify Insights, a series of automotive, home, and health studies focusing on the topics that impact us all. Through expert analysis of over 4 million car insurance applications and an array of top data sources, the Insurify Insights team produces new data-driven articles, trend analyses, regional superlatives, and national rankings every week. See Insurify Insights as featured in Forbes, Fox News, USA Today, NPR, and more.