13 Million High-Risk Homes Outside FEMA Flood Zones

Nearly 13 million properties across the United States are classified as high-risk for flooding by the climate-risk firm First Street, yet they are situated outside the Federal Emergency Management Agency's (FEMA) designated Special Flood Hazard Areas, according to a report released last week by the Government Accountability Office (GAO). This significant discrepancy highlights a potential vulnerability for homeowners who may believe their properties are safe from flood damage due to their location on FEMA's maps. A substantial portion of this mismatch is attributed to heavy rainfall, also known as pluvial flooding. First Street's analysis indicates that 62% of these high-risk properties outside FEMA's zones face rainfall as their primary flood threat. Pluvial flooding occurs when precipitation exceeds the capacity of the ground and drainage systems to absorb or channel water away, leading to accumulations that can inundate streets and homes, even in areas not traditionally associated with riverine or coastal flood risks. FEMA's mapping methodology, which originated from technologies better suited for modeling river and coastal flooding, appears to have a blind spot for this type of widespread rainfall-induced inundation. The implications of this gap are amplified by the current meteorological outlook. The National Oceanic and Atmospheric Administration (NOAA) has reported a greater than 90% probability that the current El Niño will develop into a "very strong" event this fall and winter, with a forecast for wetter-than-normal conditions across much of the southern United States. This confluence of a potentially severe El Niño and the underestimation of flood risk on FEMA maps could expose millions of homeowners to significant financial and physical damage. Furthermore, properties identified as high-risk but located outside FEMA's zones are less likely to have federal flood insurance coverage. Data from April indicates that approximately 43% of properties within Special Flood Hazard Areas held National Flood Insurance Program (NFIP) coverage, in stark contrast to the mere 2% of properties outside these zones that were insured through the program. This disparity suggests that homeowners' decisions regarding flood insurance are more heavily influenced by FEMA's map boundaries than by the actual underlying flood risk, potentially leaving many underinsured or uninsured when disaster strikes. The GAO report underscores the need for updated flood risk assessment and mapping to more accurately reflect the evolving threats posed by climate change and extreme weather events.