Flood Zones

An area the Federal Emergency Management Agency (FEMA) labels based on its likelihood for flooding.
flood zones definition

What Are Flood Zones?

The Federal Emergency Management Agency (FEMA) maps areas across the country and labels them based on their flood risk or type of flooding. That’s what flood zones are in a nutshell: shorthand for how likely flooding is in any given area.

Many homeowners think they only need flood insurance in high-risk areas, but that’s not the case. Every area is technically a flood zone – it’s just a question of how much flooding may occur. There are low, moderate, and high-risk zones, and flood claims happen in all of them.

Flood zones are used to determine flood insurance requirements and costs.

What Is a Special Flood Hazard Area (SHFA)?

A Special Flood Hazard Area (SFHA) is an area that is required to have flood insurance. Flood zones A, AO, A1-A30, AE, A99, AH, AR, AR/A, AR/AE, AR/AH, AR/AO, AR/A1-A30, V1-V30, VE, and V are all SHFAs.

If your home is in any of these zones and you have a federally backed mortgage, you’re required to have flood insurance.

Letter Grades and Flood Risk

FEMA gives each zone a letter grade based on the type and likelihood of flooding. Zones with a letter grade of A or V are considered high-risk areas with a one in four chance of flooding during a 30-year mortgage period. Those with letter grades of B, C, or X are considered low to moderate risk zones but still account for 20 to 25 percent of National Flood Insurance Program (NFIP) claims each year.

Those in A and V zones may have subgrades of risk denoted by another letter or number. And anyone in Zone D sits in an undetermined risk zone. Let’s look at each zone in more detail.

Zone A: High-Risk Flood Zones

Zone A denotes areas that are at high risk for flooding and encompasses A, AO, A1-A30, AE, A99, AH, AR, AR/A, AR/AE, AR/AH, AR/AO, AR/A1-A30. Flood insurance is required in Zone A because of its likelihood of experiencing a 100-Year Flood – a flood that has a one percent annual chance of happening.

Flood Zone A

Flood Zone A is a high-risk flood zone that has a one percent chance of flooding each year. Over the course of a 30-year mortgage, the likelihood of a flood is 26 percent. There are no detailed analyses of areas in Flood Zone A, so there are no depths or base flood elevations in this zone.

Flood Zone AE, A1-A30

Flood Zone AE is a newer version of what used to be Flood Zones A1-A30. These zones have a base flood elevation (BFE). The BFE is used to determine the rate as shown in FEMA’s Flood Insurance Rate Map (FIRM). These areas are subject to a one percent chance of flooding annually. These are mandatory flood insurance areas.

Flood Zone AH

Those living in Flood Zone AH also have a one percent annual likelihood of flooding. This flooding is generally labeled with the probability of one to three feet of water that pools in areas. True to Flood Zone A, this area has a 26 percent chance of flooding over the course of a 30-years mortgage. These are mandatory insurance zones that have BFEs derived at selected intervals on the map.

Flood Zone AO

Flood Zone AO is a specific zone for properties located near river or stream flood areas. These areas still have a one percent chance of flooding each year with a 26 percent chance of flooding over the life of a 30-year mortgage. Flood depths are expected to range from one to three feet making these areas a required flood insurance zone.

Flood Zone AR

Temporary flood insurance is required in Flood Zone AR. This zone has an increased flood risk while local authorities build or restore a flood control system like a levee or dam. The rates for Zone AR will not exceed the rates for an unnumbered A zone as long as the structure is built in compliance with Zone AR floodplain management regulations.

Flood Zone A99

Those in Flood Zone A99 are near completed or nearly-completed federal flood protection systems like a dam, dike, or levee. These areas are still subject to the one percent annual flood risk and this zone rating can only be used when the protection system progress meets certain requirements. This is a required flood insurance zone.

Zone V: High-Risk Coastal Zones

Zone V, VE, and V1-V30 are coastal regions with more risk of storm surges in addition to other forms of flooding. They are considered at risk from the velocity of coastal waves. These are mandatory insurance zones where residents with a federally backed mortgage are required to have flood insurance.

Flood Zone V

Like Flood Zone A, Flood Zone V has a one percent annual chance of experiencing a flood and a 26 percent chance of flooding over the course of a 30-year mortgage. This zone does not provide BFE for homes in it but is considered high-risk with mandatory flood insurance requirements.

Flood Zone VE, V1-V30

Unlike the unnumbered Flood Zone V, the numbered zones have a flood map with BFEs determined within the zone. These have the same probability of flooding as Flood Zone V and have mandatory flood insurance requirements.

Zones B, C, and X: Low and Moderate Risk Zones

Those in Flood Zones B, C, and X zones live in areas with low-to-moderate flood risk. The overall annual risk is 0.2 percent or less (in other words, a 500-year flood chance). Flood insurance is typically not required in these zones, but it’s usually still a smart proactive measure.

Flood Zone B and Zone X (Shaded)

These are moderate-risk flood zones. The chance of a flood is somewhere between the 100-year and 500-year flood. These areas are typically protected by levees or have shallow flooding areas. Flood depths average less than one foot and drainage is less than one square mile. These flood zones are not a Special Flood Hazard Areas.

Flood Zone C and Zone X (Unshaded)

Both Flood Zone C and Zone X (unshaded) are low-risk areas with a 0.2 percent chance of an annual flood. These zones usually have minimal flooding though there may be some ponding or local drainage problems. Zone X in particular is considered to be outside of the 500-year flood area and is protected from the 100-year flood by a levee.

Zone D: The Great Unknown

Flood D is designed to catch all other risk areas that are not defined by other flood zones. No hazard risk analysis has been done in these regions yet, so flood insurance is generally not mandatory. Flood rates in this zone reflect the uncertainty of the flood risk.

Need helping figuring out your flood zone? We can help with that when you apply for a flood insurance quote. It’s fast, easy, and free!

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