Homeowners Insurance
Flood Risk Models Vary Widely — Here's What You Need to Know (and How to Mitigate Threats)
Many Americans rely on the Federal Emergency Management Agency (FEMA) to provide accurate information on whether their properties are at risk of flooding. However, according to new 2022 data from First Street Foundation, many properties outside FEMA flood zones may be at risk for flooding.
ValuePenguin home insurance expert Divya Sangameshwar cautions that flood zone risk levels aren’t guaranteed. Homeowners who think they’re safe because they live outside a high-risk flood zone should think twice before opting out of flood insurance.
"Ninety-nine percent of U.S. counties have been affected by a flood in the past 25 years," Sangameshwar says. "The flood maps used to determine your home’s flood risk are built using historic flood data, which may not accurately capture the growing flood risk from climate change."
In this study, we compare FEMA’s Special Flood Hazard Areas (SFHAs) with the First Street Foundation data on properties at risk of flooding. We go over which states are at the highest risk for flooding, where the perceived flood risk is most different and which states may see even more risk in the future.
- Key findings
- Depending on the model, Louisiana or West Virginia is at the highest risk for flooding
- Flood risk is most underestimated in Hawaii and Alaska
- Climate change will increase risk for properties in coastal states — and insurance rates will climb, too
- How to mitigate flood risk at your property
- Methodology
Key findings
- FEMA data indicates properties in Louisiana are most at risk for flooding, but a broader First Street Foundation model suggests West Virginia would be the hardest hit. Louisiana has the highest percentage of properties in FEMA’s Special Flood Hazard Areas (23.5%). But the First Street Foundation model — which looks at all properties in a state, not just those in flood areas — shows West Virginia with the highest percentage of homes that would be flooded in a 100-year storm event (29.3%).
- Perceived flood risk is most different in Hawaii. Just 3.2% of Hawaii properties are in a FEMA flood hazard area, but the First Street Foundation model indicates that 26.1% of properties in the state face at least some risk — a 22.9 percentage point difference.
- With flood mapping not yet available in many parts of the state, Alaska properties see a similarly high jump in the percentage of properties at risk. 0.5% of Alaska properties are included in a FEMA flood hazard area, the lowest percentage of any state. However, the First Street Foundation model finds that 51,308 Alaska properties are at risk of flooding — 13.8% of the state’s properties.
- With climate change on the rise, Louisiana is expected to experience the biggest jump in the percentage of properties at risk of flooding. In Louisiana, 24.5% of properties are at risk for flooding, according to First Street Foundation, but that’s predicted to increase to 38.0% in 30 years. Comparatively, in Florida — the state with the second-highest jump in flood risk — the percentage is expected to increase from 23.3% to 26.6%.
How we analyzed flood risk
The FEMA and First Street Foundation models identify areas at substantial risk of flooding as those with at least a 1% chance of being inundated by a flood event in any given year. This flood event is also referred to as a base flood or 100-year flood.
Specifically, FEMA applies its SFHA classification to areas with a 1% (or higher) annual chance of flooding that will be protected by a federal flood control system where construction has reached specified legal requirements.
ValuePenguin researchers analyzed data from FEMA’s SFHAs and First Street Foundation’s 100-year flood model to determine which states have the highest percentage of properties with at least a 1% risk of flooding in any given year.
The First Street Foundation data was released in April 2022. FEMA timelines are far harder to nail down. As of a 2019 First Street Foundation report, 75% of FEMA flood maps were older than 5 years old, with 11% dating back to the 1970s or 1980s — amplifying the limitations of the FEMA maps in some cases.
Depending on the model, Louisiana or West Virginia is at the highest risk for flooding
While FEMA classifies 8.4 million properties as being in a flood hazard area, the First Street Foundation flood model identifies 16.5 million properties at risk. That’s not the only discrepancy between the two models — the states with the highest percentage of properties at risk are also different.
Louisiana has the highest percentage of properties in FEMA SFHAs at 23.5%.
States with the highest percentage of properties in a FEMA Special Flood Hazard Area
State | Total properties | Number of properties in a FEMA SFHA | Percentage of properties in a FEMA SFHA |
|---|---|---|---|
| Louisiana | 2,365,126 | 555,622 | 23.5% |
| Florida | 8,974,526 | 1,693,584 | 18.9% |
| Mississippi | 1,903,874 | 243,798 | 12.8% |
| New Jersey | 3,449,288 | 387,238 | 11.2% |
| West Virginia | 1,427,366 | 132,772 | 9.3% |
| Arkansas | 1,915,572 | 149,192 | 7.8% |
| South Carolina | 2,615,784 | 197,101 | 7.5% |
Source: ValuePenguin analysis of First Street Foundation data
However, the First Street Foundation flood model identifies a higher percentage of West Virginia properties at risk. In fact, 29.3% of West Virginia properties are at risk in the First Street Foundation flood model, a spike from the 9.3% in FEMA flood hazard areas. That’s an additional 284,977 properties.
States with the highest percentage of properties at risk of flooding in the First Street Foundation model
State | Total properties | Number of properties with 1% risk of flooding | Percentage of properties with 1% risk of flooding |
|---|---|---|---|
| West Virginia | 1,427,366 | 417,749 | 29.3% |
| Hawaii | 380,835 | 99,402 | 26.1% |
| Louisiana | 2,365,126 | 579,038 | 24.5% |
| Florida | 8,974,526 | 2,093,791 | 23.3% |
| Mississippi | 1,903,874 | 308,399 | 16.2% |
| Oregon | 1,804,298 | 286,130 | 15.9% |
| Montana | 892,861 | 136,196 | 15.3% |
| Idaho | 1,036,610 | 158,765 | 15.3% |
Source: ValuePenguin analysis of First Street Foundation data
The increased risk in these states could mainly be due to the First Street model accounting for climate change, while FEMA’s mapping of flood hazard zones isn't yet complete.
Contrary to FEMA hazard areas, the First Street model also analyzes current climate data and precipitation as a stand-alone risk. And West Virginia is no stranger to heavy rainfall. In fact, flooding caused by extreme rainfall is the state’s costliest and most severe natural hazard, according to the National Oceanic and Atmospheric Administration (NOAA). From 2010 to 2020, the state received 18 FEMA disaster declarations due to severe storms and flooding events.
Heavy rainfall is linked to hot weather. As temperatures rise, the number of heavy rain events will likely increase, too. In fact, another recent ValuePenguin study found that extreme heat is increasing nationally — along with heat-related deaths.
In the First Street model, Louisiana falls to third by the percentage of properties at risk. The discrepancy may be because the First Street model also considers preventive measures, some of which FEMA may not consider. Since Hurricane Katrina walloped the state in 2005, the federal government has spent $14.5 billion on flood prevention throughout Louisiana’s most at-risk areas.
Flood risk is most underestimated in Hawaii and Alaska
When comparing the FEMA Special Flood Hazard Areas and the First Street Foundation flood model, the percentage point difference among properties at risk is highest in Hawaii. While FEMA estimates 12,145 Hawaii properties are at risk of flooding, the First Street Foundation model puts its estimation at 99,402 properties — a difference of 22.9 percentage points.
Difference between properties at risk in the FEMA and First Street Foundation models
State | Total properties | Number in FEMA SFHAs | Percentage in FEMA SFHAs | Number in First Street Foundation model | Percentage in First Street Foundation model | Difference in number of properties at risk | Percentage point difference in properties at risk |
|---|---|---|---|---|---|---|---|
| Hawaii | 380,835 | 12,145 | 3.2% | 99,402 | 26.1% | 87,257 | 22.9 |
| West Virginia | 1,427,366 | 132,772 | 9.3% | 417,749 | 29.3% | 284,977 | 20.0 |
| Alaska | 372,298 | 1,911 | 0.5% | 51,308 | 13.8% | 49,397 | 13.3 |
| Montana | 892,861 | 28,951 | 3.2% | 136,196 | 15.3% | 107,245 | 12.1 |
| Idaho | 1,036,610 | 37,721 | 3.6% | 158,765 | 15.3% | 121,044 | 11.7 |
| Oregon | 1,804,298 | 85,455 | 4.7% | 286,130 | 15.9% | 200,675 | 11.2 |
| Vermont | 312,204 | 12,786 | 4.1% | 46,103 | 14.8% | 33,317 | 10.7 |
| Wyoming | 339,156 | 8,239 | 2.4% | 40,460 | 11.9% | 32,221 | 9.5 |
Source: ValuePenguin analysis of First Street Foundation data
The difference may be because of how each model analyzes coastal flood risk. The First Street Foundation flood model utilizes tide gauge readings from NOAA to identify trends in sea-level rise and the frequency of tidal surges, while the FEMA hazard areas don’t.
According to NOAA data, sea levels on Hawaii’s coast are rising at a rate of around 1 inch every four years. Additionally, tidal surges are on the rise. In Honolulu alone, high-tide flooding has increased from six days a year in the 1960s to 11 now, according to Honolulu's Climate Change Commission.
Amid flood zone mapping challenges, FEMA underestimates flood risk in Alaska
Following Hawaii, the percentage point difference in properties at risk is highest in West Virginia (20.0%), then Alaska (13.3%). While we’ve already covered West Virginia, Alaska has unique challenges.
FEMA identifies just 0.5% of Alaska properties on the SFHA map — the lowest percentage of any state. That comes to 1,911 properties in total. However, the First Street Foundation model finds that 51,308 Alaska properties are at risk of flooding — 13.8% of the state’s properties.
This discrepancy may be because most of Alaska hasn’t been mapped by FEMA. Of more than 40 Alaska coastal communities that have experienced major flooding, only six participate in FEMA’s National Flood Insurance Program (NFIP), according to a study conducted by the Alaska Department of Natural Resources. Only participants in the NFIP are included in FEMA’s flood mapping program — meaning the rest of the state isn’t included in SFHAs.
Other efforts to map Alaska’s flood risk are few and far between. For many western Alaska communities, the only floodplain assessments were conducted by the U.S. Army Corps of Engineers in the 1990s, according to the study. Almost 30 years later, these documents are still used as the baseline for planning by most communities in western Alaska — even though many have experienced at least one flood.
As far as why many Alaska communities are at risk, several environmental factors are at play. For the state’s western communities, severe erosion and disappearing sea ice cause regular coastal flooding, while the northern communities experience disastrous storm surges and cyclones from the Arctic.
With a large portion of Alaska’s communities scattered along the coast, the damage from these storms and coastal surges is often widespread. For example, a 2011 storm led to disaster declarations for 37 Alaska communities on over 1,300 miles of coastline — which is more coastline than in the western contiguous U.S.
Climate change will increase risk for properties in coastal states — and insurance rates will climb, too
With sea levels on the rise and tropical storms growing in volatility, many more properties will be at an increased risk for flooding in 30 years — particularly in coastal states. According to First Street Foundation, Louisiana will see the biggest increase in properties at risk, jumping from 24.5% of properties at risk now to 38.0% in 30 years. That means it’ll also overtake West Virginia as the state with the highest percentage of properties at risk of flooding.
Comparatively, in Florida — the state with the second-highest percentage increase — the percentage of properties at risk will increase from 23.3% now to 26.6% in 30 years.
First Street Foundation future estimation for properties at risk
State | Total properties | Number in current First Street Foundation model | Percentage in current First Street Foundation model | Number in 30-year First Street Foundation model | Percentage in 30-year First Street Foundation model | Percentage change |
|---|---|---|---|---|---|---|
| Louisiana | 2,365,126 | 579,038 | 24.5% | 899,548 | 38.0% | 55.4% |
| Florida | 8,974,526 | 2,093,791 | 23.3% | 2,384,235 | 26.6% | 13.9% |
| New Jersey | 3,449,288 | 431,362 | 12.5% | 483,494 | 14.0% | 12.1% |
| South Carolina | 2,615,784 | 323,609 | 12.4% | 360,248 | 13.8% | 11.3% |
| Texas | 11,957,175 | 1,257,223 | 10.5% | 1,405,819 | 11.8% | 11.8% |
| Rhode Island | 383,730 | 31,674 | 8.3% | 35,046 | 9.1% | 10.7% |
| California | 11,336,595 | 1,395,118 | 12.3% | 1,540,305 | 13.6% | 10.4% |
| Delaware | 422,994 | 46,627 | 11% | 51,478 | 12.2% | 10.4% |
| Nevada | 1,208,983 | 85,054 | 7.0% | 93,861 | 7.8% | 10.4% |
| Virginia | 3,794,895 | 367,130 | 9.7% | 403,907 | 10.6% | 10.0% |
Source: ValuePenguin analysis of First Street Foundation data
Overall, coastal states make up nine of the top 10 states with the highest percentage increases. That’s unsurprising, given that coastal communities feel the firsthand effects of climate change. In fact, NOAA researchers predict sea levels will rise 10 to 12 inches by 2050, causing tidal floods and storm surges to reach further inland. By 2050, the NOAA predicts "moderate" flooding to occur more than 10 times as often as today.
Coastal states will see an increase in their insurance rates, too. Last year, FEMA announced that it’s actively updating the National Flood Insurance Program's risk rating methodology to — among other things — take NOAA’s sea-level rise estimates into account for its pricing model.
According to a 2021 ValuePenguin study on the new risk rating model, most homeowners can expect an increase in their insurance premium costs (77%). Those on the coast — mostly in Texas (86%), Florida (80%), Louisiana (80%) and New Jersey (79%) — can expect to see the highest percentages of policies with premium increases.
How to mitigate flood risk at your property
With flood risk on the rise, taking steps to mitigate your property’s risk can be crucial in preventing hefty and unexpected damage. Sangameshwar recommends all homeowners consider insuring their property against flood damage — more than 90% of U.S. owner-occupied homes have homeowners insurance, but just 2.6% have NFIP flood insurance policies.
"A single flood has led to an average of $52,000 in damages, and just 1 inch of water can cause as much as $25,000 in damages," Sangameshwar says. "While paying $613 to $1,648 a year for flood insurance might be expensive for some families, going without could decimate your finances."
For Americans looking to prevent flood damage, Sangameshwar also offers the following advice:
- Research local flood history before buying. Before buying a home, it’s important to understand how much flood risk you’ll be assuming. "It’s now common to include flood risk information on multiple listing services (MLSs)," Sangameshwar says. "Sellers are also obligated to disclose information related to flooding, such as whether the property flooded before, so make sure you ask."
- Check with your mortgage provider about your flood insurance requirements. "If you live in a high-risk flood zone, your mortgage lender will require you to get flood insurance," Sangameshwar says. Homes located in high-risk zones will need an elevation certificate, or EC. The EC shows your home’s elevation in relation to how high floodwater will reach in the event of a major storm. This gives insurance companies an idea of how much risk is involved, which may impact your premium.
- Know what your insurance will and won’t cover. "Floor insurance covers flooding from heavy rain, rising rivers or flooding due to a natural disaster," Sangameshwar says. "They won’t cover water damage from a burst pipe — that would fall under your homeowners insurance policy. Additionally, insurance policies won’t cover you for water damage or flooding that comes from poor maintenance."
- Don’t wait until a storm is headed your way before buying flood insurance. "Most flood insurance policies have a 30-day waiting period before coverage is activated," Sangameshwar says. "The best time to review your flood insurance is at the beginning of the year."
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Flood-proof your home. Depending on your home’s level of risk, small changes can make a big difference. Sangameshwar recommends the following four steps to flood-proof your home:
- Keep your gutters in good condition. Faulty gutters can flood basements. Additionally, if your insurer finds your gutters are faulty or clogged, it may prevent you from receiving an insurance claim.
- Seal your basement. "Basements are the part of your home most likely to flood," Sangameshwar says. Use weather strips or caulk around openings to stop water intrusions.
- Don’t plant too close to your house. The roots of plants and trees in the ground can crack concrete and restrict the drainage of water.
- Consider installing extra equipment. A backwater valve can help close off drains to municipal sewer lines, which can prevent major flooding in your home in the event of a backup. Additionally, Sangameshwar recommends installing a sump pump or a French drain to further prevent unwanted moisture.
Methodology
ValuePenguin researchers analyzed data released in 2022 in the First Street Foundation flood model, which includes the most up-to-date FEMA SFHA data, to determine the percentage point difference in properties at significant risk of flooding. Properties with significant risk are defined as those with at least a 1% chance of being inundated by a flood event in any given year. The 1% annual chance flood is also referred to as a base flood or 100-year flood.
Because FEMA applies its SFHA classification to areas with a 1% (or higher) annual chance of flooding that will be protected by a federal flood control system where construction has reached specified legal requirements, ValuePenguin researchers specifically analyzed the 100-year flood models.
ValuePenguin researchers also analyzed First Street Foundation’s 100-year flood model predictions for 30 years in the future, which incorporate anticipated environmental changes like sea-level rise, changing precipitation patterns, and warming sea surface and atmospheric temperatures. We then compared the predictions to the current 100-year flood model.