Charleston, SC

Hurricane Hugo made landfall near Charleston in September 1989 as a Category 4 storm, producing surge flooding and wind damage that remains the city's benchmark wind event more than three decades later. Charleston's flood score of 92 sits at the 97th national percentile; its hurricane score of 89 sits at the 95th. But the more persistent daily-life issue is tidal flooding: the historic peninsula in 29401 experiences regular street and property inundation tied to sea-level and tidal cycles—not storm events. The South Carolina flood of 2015, which dropped more than 20 inches of rain in some areas within 24 hours, added a rainfall-flooding layer on top of the tidal baseline. What we noticed: the peninsula's tidal flooding is not a future-risk scenario. It is an existing operational constraint. Buyers in 29401 deal with periodic access disruption, basement moisture, and storm drain overflow as recurring maintenance items, independent of named hurricane seasons. James Island's marsh and surge exposure rise quickly; insurance for 29412 properties reflects that directly. Annual premiums range from $2,600 to $6,700, with flood insurance required across most low-lying and coastal-adjacent properties. Historic homes carry additional resilience retrofit costs beyond the premium line—preservation constraints can limit the scope of practical flood-proofing options. Heat at the 77th national percentile is moderate but compounds outage impact after major storms: long post-storm heat exposure creates a livability pressure that insurance settlements do not cover. Hugo established the wind baseline. Tidal flooding establishes the daily-life baseline. Charleston buyers need both maps—and a carrying-cost model that accounts for the nuisance flooding that occurs whether or not a named storm ever arrives.

— Open Data Collective