Every county page on this site starts with a rating such as “Very High” or “Relatively Low”. That rating comes from FEMA’s National Risk Index, a free public dataset that scores all 3,144 counties in the 50 states and DC for 18 natural hazards. The rating is useful, but it is easy to misread. Here is what it measures and how to use it.
What does the risk rating measure?
The National Risk Index combines three things for each county:
- Expected annual loss: the dollar damage a county can expect from natural hazards in an average year, counting buildings, crops and a value for lives lost and injuries.
- Social vulnerability: how hard it is for the people who live there to prepare for and recover from a disaster, based on factors like income, age and housing.
- Community resilience: how well the local community is set up to bounce back, based on things like health care access and local government capacity.
Expected loss is the largest part. A county with high expected loss, more vulnerable residents and weaker resilience ends up with a higher score.
Why does my big county look so risky?
Because it has more to lose. Harris County, Texas, has 4.7 million people and about $839 billion in buildings, so even ordinary storms cause large dollar losses. FEMA expects about $2.2 billion a year there, which puts it in the top 1% of counties.
That doesn’t mean each home in Harris County is in more danger than a home in a small coastal county. That is why each county page here also shows the expected loss per resident. Harris County works out to about $469 per resident a year. Charleston County, South Carolina, is smaller but higher per person, at about $1,226.
What is the difference between the score and the rating?
The score is a percentile from 0 to 100. A score of 80 means the county’s risk is higher than 80% of US counties.
The rating is one of five groups: Very Low, Relatively Low, Relatively Moderate, Relatively High and Very High. Most counties sit in the lower groups. Out of 3,144 counties, 1,345 are Very Low and 1,200 are Relatively Low. Only 17 are Very High.
That is why a county can be rated “Relatively Low” and still score higher than two thirds of counties. Most counties have low risk, so being above the middle doesn’t take much.
Which hazards does it cover?
The index covers 18 hazards: avalanche, coastal flooding, cold wave, drought, earthquake, hail, heat wave, hurricane, ice storm, inland flooding, landslide, lightning, strong wind, tornado, tsunami, volcanic activity, wildfire and winter weather.
Each county page lists them in order of expected loss, so the costliest hazard comes first. Inland flooding tops the list in 2,269 counties, more than any other hazard. Cold waves come first in 201 counties and hurricanes in 200.
Is it a prediction for my house?
No. The index is a county-level average. Risk inside a county varies a lot: a home on a hill and a home beside a creek in the same county face very different flood risk.
For a specific address, check the FEMA Flood Map Service Center for the flood zone, ask your insurer for a quote, and look at the property’s own history, such as past flood claims (sellers in many states must disclose these).
How often is the data updated?
FEMA updates the National Risk Index about once a year. The version used on this site is dated December 2025. Disaster declarations change more often, so we refresh those every week. Each county page shows the date of both.
Questions people ask
Is a “Very Low” county safe from disasters? No county is free of risk. A Very Low rating means the expected losses are small compared with other counties. Storms, floods and fires can still happen anywhere.
Why is my county rated high for a hazard I’ve never seen? The index uses long records and models, not only recent memory. Earthquake and hurricane ratings, for example, reflect rare but very costly events.
Can a rating change? Yes. New data, new buildings and population changes all move the numbers. A county that grows quickly will often see its expected loss rise.
Where does the data come from? FEMA’s National Risk Index (December 2025) and OpenFEMA disaster declarations. This site is independent and is not part of FEMA or any government agency.