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Data updated October 22, 2026

Data updated October 22, 2026

Sea level rise and property: reading the projections and maps

Updated October 22, 2026

Federal scientists project 10 to 12 inches of sea level rise along US coasts between 2020 and 2050, with the range widening sharply after that. NOAA's inundation maps show which land sits low enough to be under water at high tide for a given rise; they are not flood zone maps and do not set insurance requirements.

Sea level rise matters to property in two ways: it raises the baseline for every high tide and storm surge, and it slowly moves the line where ordinary tides reach land. The federal projections give the expected amount of rise; NOAA’s maps show where a given amount would put water at high tide. Neither tells you a building’s current flood zone or insurance requirement.

What the 2022 federal projections say

The 2022 Sea Level Rise Technical Report, produced by an interagency task force, projects that sea level along the US coastline will rise 10 to 12 inches on average between 2020 and 2050. It also projects that coastal flooding will occur, on average, more than 10 times as often in 30 years as it does today.

The report uses five scenarios defined by global mean sea level rise by 2100: Low (0.3 meters, about 1 foot), Intermediate-Low (0.5 meters), Intermediate (1.0 meter), Intermediate-High (1.5 meters) and High (2.0 meters, about 6.6 feet) (earth.gov scenario FAQ). The scenarios are close together through 2050 and diverge after that, so near-term figures are much more certain than end-of-century ones.

Local rise differs from the global figure because of ocean circulation, gravitational effects of ice loss and land motion. The report therefore publishes relative projections at individual tide gauges.

Virginia Key projections in feet

The nearest long-term NOAA gauge to Miami is Virginia Key, Biscayne Bay (station 8723214). These are the report’s median projections at that gauge, relative to sea level in 2000, converted from centimeters to feet.

Scenario Rise by 2050 Rise by 2100
Low 0.9 ft 1.5 ft
Intermediate-Low 1.0 ft 2.2 ft
Intermediate 1.1 ft 3.7 ft
Intermediate-High 1.3 ft 5.3 ft
High 1.5 ft 7.0 ft

By 2050 the spread across all five scenarios is about 8 inches (21 centimeters). By 2100 it is more than 5 feet, which is why long-lived decisions, such as building elevation or a 30-year mortgage on low ground, are usually tested against more than one scenario.

What NOAA’s Sea Level Rise Viewer shows

NOAA’s Sea Level Rise Viewer maps the inland extent and relative depth of inundation from 0 to 10 feet above mean higher high water (MHHW), in half-foot steps. MHHW is the average of the higher high tide each day over the 19-year tidal datum epoch, so each layer shows land that would be under water on a typical high tide after that much rise, with no storm involved. NOAA’s viewer FAQ sets out the method and limits:

  • Connected areas only, in blue. Water is mapped where it can reach the land from the ocean according to the elevation model.
  • Low-lying areas, in green. These are below the water level but not connected to the ocean in the elevation data. NOAA says a more detailed analysis is needed to know whether they would flood.
  • Mapping confidence. A separate layer shows where inundation is mapped with at least 80% confidence and where confidence is lower, based on errors in the lidar elevation and the tidal surface. NOAA describes the edge as a zone, not a hard line.
  • What is left out. The maps do not account for erosion, subsidence, future construction or changes to the shoreline, and they do not model pipes, culverts or other drainage features in detail. Major federal leveed areas are assumed to be protected.
  • Screening use. NOAA says the data should be used only as a screening-level tool, and recommends rounding to the nearest one-foot increment when viewing impacts.

The viewer’s Local Scenarios tab links water levels to the 2022 scenarios, so a mapped water level such as 3 feet can be compared directly with when each scenario projects that much rise locally.

Miami-Dade buildings inside the 3 ft extent

For our ZIP reports we checked every building in the Miami-Dade ZIPs we cover against NOAA’s connected-inundation extents at 1, 2 and 3 feet above MHHW. The building counts come from the USA Structures dataset; a building counts if its center point falls inside the extent, regardless of depth. Across the 78 Miami-Dade ZIPs we cover, 6,213 of about 551,550 buildings (1.1%) are inside the 3 ft extent, 586 at 2 ft and 189 at 1 ft.

The exposure is concentrated on the barrier islands and along Biscayne Bay:

ZIP Area Buildings inside 3 ft extent Share of buildings
33140 Miami Beach 1,201 31%
33139 Miami Beach 1,190 34%
33141 Miami Beach 1,149 30%
33154 Miami Beach 493 22%
33138 Miami 378 5%
33181 North Miami 371 14%
33160 North Miami Beach 367 15%

Most of these buildings are outside the 1 ft extent; in ZIP 33139, for example, 20 buildings are inside at 1 ft and 160 at 2 ft. Under the Intermediate scenario, Virginia Key passes 3 feet of rise before 2100, while under the Low and Intermediate-Low scenarios it does not reach 3 feet this century. The extents are ocean-connected only, so the counts leave out low-lying unconnected areas and say nothing about drainage or groundwater.

High tide flooding at Virginia Key

NOAA counts days each year when water at a gauge exceeds its minor (high tide) flood threshold (NOAA CO-OPS). At Virginia Key, the calendar-year count was never more than 2 days in any year from 1995 through 2014. From 2015 through 2025 it ranged from 0 to 9 days, with 9 in 2019 and 7 in 2025, and the gauge recorded one day above the moderate threshold in 2017. Counts swing from year to year with weather and tides, but the higher baseline since 2015 is what the federal projections describe.

How this differs from FEMA flood zones and NFIP rating

FEMA flood maps and NOAA’s sea level rise maps answer different questions.

  • FEMA flood zones show the flood hazard FEMA has mapped for a community. The Special Flood Hazard Area (Zones A and V) triggers mandatory flood insurance for federally backed and regulated mortgages; see flood insurance requirements. Miami-Dade’s new flood maps take effect February 19, 2027 (what changes).
  • NOAA’s extents show land below a chosen water level on an ordinary high tide, for planning and screening. They carry no regulatory requirement.
  • NFIP premiums under Risk Rating 2.0 do not use flood zones to set the price. FEMA says the rating considers flood frequency, multiple flood types including storm surge and coastal erosion, distance to water, and property characteristics such as elevation and the cost to rebuild (FEMA, Risk Rating 2.0).

A building can be outside the SFHA and still sit inside NOAA’s 3 ft extent, or inside the SFHA and well above it. For a purchase, check all three: the current zone, the elevation of the lowest floor, and how far that elevation sits above today’s high tide.

Questions

How much will sea level rise in Miami by 2050?

At NOAA's Virginia Key gauge, the 2022 federal scenarios project about 0.9 to 1.5 feet of rise by 2050 relative to 2000, depending on the scenario, with about 1.1 feet under the Intermediate scenario.

Is NOAA's sea level rise map the same as a FEMA flood zone?

No. NOAA's viewer shows land below a chosen water level above mean higher high water on an ordinary high tide. FEMA flood zones show the mapped flood hazard used for mandatory flood insurance purchase and floodplain rules.

Does a property inside the 3 ft sea level rise extent need flood insurance?

Not because of the sea level rise map. Federal mandatory purchase depends on whether the building is in a FEMA Special Flood Hazard Area and has a federally backed or regulated mortgage.

Sources

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