San Francisco, CA

San Francisco's earthquake score of 91 sits at the 97th national percentile—the defining physical risk for this market, and the one that most clearly separates serious buyer diligence from casual assumption. The 1989 Loma Prieta earthquake destroyed sections of the Bay Bridge, collapsed the Cypress Freeway, and damaged hundreds of buildings across the city. That event remains the region's modern baseline for what seismic disruption actually costs in a dense urban environment. Atmospheric river flooding in 2023 added a different pressure: drainage constraints and hillside failure in neighborhoods that rarely appear on coastal flood maps. Our read: the Mission District's older building inventory and limited AC penetration create a heat and retrofit cost combination that the city's fog-era reputation obscures. Castro and Eureka Valley's steep grades and older homes complicate seismic upgrades in ways that flat-parcel buyers do not encounter. Outer Richmond's coastal edge changes flood and infrastructure assumptions relative to the urban core. Earthquake insurance remains a separate budgeting decision—optional but economically significant, especially for older multifamily and condo buyers where building retrofit status can determine both insurability and cost. Annual premiums range from $1,400 to $3,800, lower than South Florida markets, but the retrofit cost exposure is additive and can reach six figures in older buildings. Flood scores here sit at the 62nd national percentile—moderate—with heat at the 56th, low. The city's primary climate diligence question is not about warming summers. It is about how aging infrastructure performs when the next significant seismic event arrives and whether retrofit investments have been made before that test, not after.

— Open Data Collective