18 FEMA Flood Zones for Flood Insurance Requirements

While the principle analysis is based on a 1 percent rule of the 100-year floodplain, many areas in FEMA’s flood map have the propensity to sustain multiple floods every 100 years — and some areas are known to flood nearly every year.

Let’s take a look at the different flood zone categories and break down every one of the 18 FEMA flood zone designations across the U.S.

There are three different flood zones in the country: high-risk, moderate-to-low-risk and undetermined risk. While each zone may be prone to floods, it’s worth noting that some areas have not had any flood analysis conducted on their grounds yet. It’s worth noting, too, that depending on your flood zone, insurance costs may vary. The greater your risk, the more likely it is that you’ll need to use your flood insurance policy while you live there. 

Given the letter designations of A or V, homes and businesses in high-risk flood zones are at the most risk of sustaining a flood every year. Homes inside this designation are called Special Flood Hazard Areas (SFHA) and face a 25 percent chance of sustaining at least one flood during their 30-year mortgage and are required by their mortgage company to maintain adequate flood insurance, either through a private carrier or through FEMA’s National Flood Insurance Program, during the entire term of the loan.

Flood zones with a letter A designation are inland areas while flood zones with a letter designation of V are coastal areas.

Designations B, C and X fall inside the moderate-to-low-risk flood zones and account for more than 20 percent of the flood insurance claims filed with FEMA’s National Flood Insurance Program each year.

While homeowners in these designations typically aren’t required by their mortgage lender to purchase flood insurance, it is highly recommended for everyone in these areas (homeowners, business owners, landlords and tenants) to purchase and maintain adequate flood insurance while you live there.

Undetermined risk flood zones in the U.S. may still be at risk of sustaining a flood at least once every 100 years, but no analysis has been conducted in the area. Flood insurance is still available in this zone and its purchase is strongly advised.

There are 18 flood zones in the U.S. that have been designated by FEMA, which uses cutting-edge mapping technology to determine the flood risks of areas throughout the country and create a map for the general public to use. These designations are used by insurance companies and mortgage lenders and are aimed to help the general public determine the flood risk of their home or business.

Areas in flood zone A have a 1 percent chance of flooding per year and a 25 percent chance of flooding at least once during a 30-year mortgage. Since there hasn’t been detailed hydraulic analysis in these areas, the base flood elevation and depths have not been determined.

Areas in flood zone AO have been given a river, stream or pond flood hazard designation, meaning there is a 1 percent chance of sustaining 1 foot to 3 feet of floodwaters each year and a 25 percent chance of the same thing at least once during a 30-year mortgage.

Flood zone AH includes areas of ponding from larger bodies of water, given the designation a 1 percent chance of annual flooding and a 25 percent chance of at least one flood every 30 years with an average depth of 1 foot to 3 feet.

Flood zones A1-A30 depict numbered zones in FEMA’s flood maps. These designations in the Flood Insurance Rate Map (FIRM) show a base flood elevation in relation to the National Geodetic Vertical Datum (NGVD), which is the mean sea level in the U.S.

Flood zone AE is slowly replacing the A-numbered zones above and depicts similar designations in the FIRM based on NGVD base flood elevations.

Flood zone A99 is unique in its distinction because it depicts areas in the country with a 1 percent chance of annual flooding and are protected by a federal flood control system deemed mandatory by the Flood Control Act of 1936. These systems include levees, dams, dikes and other irrigation systems that allow the control of water to high-risk flood areas.

Flood zone AR are areas that have a federal flood control system nearby that has been decertified and is in the process of undergoing restoration or reconstruction to provide base flood protection to the area. They also maintain a 1 percent chance of flooding each year.

Flood zone AR/AE areas have a 1 percent chance of annual flooding as determined by FEMA’s Base Flood Elevation (BFE), which is the regulatory requirement for the elevation floodproofing structures. Areas in this designation contain a mix of flood zone AR and flood zone AE in the same area.

Flood zone AR/AO is an area with a combination of flood zones AR and AO and is given at least a 1 percent chance of annual flooding. In these areas, some homes and businesses may be protected by a water control system, such as a dam, while others are not.

Flood zone AR/A1-A30 holds a particularly distinct designation due to the temporary risk of increased flood damage given a flood control system in the area may be undergoing restoration or reconstruction. Some homes and businesses in these areas may be much more prone to flooding than others based on the location to the flood control system.

Flood zone AR/A is another zone designated by FEMA which contains a flood control system that has been temporarily decommissioned or is undergoing repairs or restoration. These areas are especially risky because the weakened flood control system is coupled with the 1 percent chance of annual flooding and a 25 percent chance of flooding at least once during a 30-year mortgage

Flood zone V is similar to flood zone A in that it represents the highest-risk flood zone in coastal areas. It’s given the Special Flood Hazard Area designation and has a 1 percent chance of annual flooding and a 25 percent chance of flooding at least once during a 30-year mortgage. These areas are especially hazardous due to being on the coast near oceans and facing immediate risk of hurricane storm surges, which can rise to 20 feet.

Flood zone VE encompasses coastal areas that have some sort of natural flood protection by sand dunes directly off the beach. These areas are still prone to a 1 percent chance of flood each year and a 25 percent chance of flood at least once during a 30-year mortgage, but they maintain a bit more protection from floodwaters due to storm surge than flood zone V.

Flood zones V1-V30 share the same number distinction of flood zones A1-A30, except these are located on coastal areas with the increased probability of storm-induced flooding. These areas share the same 1 percent annual chance of flooding and a 25 percent chance of flooding at least once every 30 years, but the flood damage may be more severe if coupled with strong winds from hurricanes or tropical storms.

Flood zone B is the first designation of moderate-to-low-risk flood zones and is predicted to flood at least once every 500 years. These areas aren’t required to have flood insurance, but we still recommend getting it if you live in these areas.

Flood zone C shares the same flood chance of at least one flood every 500 years as flood zone B, but flood zone C may contain areas that don’t meet FEMA’s requirements to be mapped as a Special Flood Hazard Area. Areas residing in flood zone C may be susceptible to ponding and local drainage problems.

Flood zone X, also known as flood zone X500, is arguably the safest flood zone designation, as it’s considered to be outside the 500-year floodplain and is also protected by a flood control system, such as a levee or dam, from the 100-year floodplain.

Flood zone D doesn’t stipulate that it’s the safest of all flood zones, it just means the area has not been mapped for floods. Areas in zone D are often sparsely populated and largely undeveloped, so there have not been any flood analysis mapping in these areas. Homeowners and business owners in flood zone D may still purchase flood insurance and are strongly encouraged to do so.

Mortgage lenders require flood insurance in high-risk FEMA flood zones.

If you’re having trouble finding flood insurance or you believe your home has been classified into the wrong zone, you may get a flood elevation certification on your home. These certificates are used to determine the risk of a home’s flooding on an individual basis, and can come in handy since FEMA’s flood zones may be outdated in many areas.