Boston, Massachusetts Flood Zones

Boston faces a combination of coastal and inland flood risks. Storm surge from hurricanes and tropical storms pushes seawater inland, while heavy rainfall simultaneously overwhelms rivers, bayous, and drainage infrastructure. This dual threat means flooding can come from multiple directions at once. The most common FEMA flood zone designations in Boston are Zone AE, Zone VE, Zone AO, Zone X. FEMA's National Risk Index estimates the county's annual expected loss from inland flooding at over $59.5M. Properties in Boston's VE zones face additional wave action risk beyond still-water flooding, which typically results in higher insurance premiums and stricter building requirements. Boston has Zone AO areas subject to sheet-flow flooding, where shallow water spreads across broad, flat terrain rather than channeling through waterways.

Combined coastal and inland flood exposure in Boston means properties may face higher premiums than areas with only one flood source. FEMA's Risk Rating 2.0 accounts for multiple flood sources, including coastal surge distance, river proximity, and rainfall-driven flooding. If your property is in a Special Flood Hazard Area (SFHA) and you have a federally regulated or government-backed mortgage, federal law generally requires your lender to ensure you carry flood insurance.

Flood maps in areas with combined coastal and inland risk are among the most complex in the FEMA system. Major storms often trigger FEMA restudies that can significantly shift zone boundaries. Letters of Map Revision (LOMR) after hurricanes may expand SFHA coverage as new storm data is incorporated. Use our free lookup tool to check the current flood zone for any Boston address.