Charleston County
South Carolina — Natural Disaster Risk Assessment
HighComposite Risk Score
National percentile: 99th
Charleston County faces high composite natural disaster risk (NRI Risk Index score 98.6, 99th national percentile), driven primarily by coastal flood and hurricane exposure. Expected annual loss across all 18 hazard types is $500M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Coastal Flood | Very High | 3.65 / yr | $36M |
| Hurricane | Very High | 0.34 / yr | $281M |
| Earthquake | High | 0.01 / yr | $118M |
| Ice Storm | High | 0.88 / yr | $2M |
| Wildfire | Medium | 0.00 / yr | $3M |
| Lightning | High | 63.33 / yr | $2M |
| Riverine Flood | Medium | 3.54 / yr | $44M |
| Cold Wave | Medium | 0.79 / yr | $7M |
| Winter Weather | Medium | 0.95 / yr | $301K |
| Heat Wave | Medium | 9.58 / yr | $2M |
| Strong Wind | Medium | 1.60 / yr | $2M |
| Tornado | Medium | 0.49 / yr | $3M |
| Hail | Low | 2.20 / yr | $451K |
| Landslide | Very Low | 0.21 / yr | $650 |
| Drought | Low | 15.28 / yr | $50K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Frequently Asked Questions
What is the overall natural disaster risk for Charleston County?
Charleston County has a composite FEMA National Risk Index score of 98.6 out of 100, placing it in the High category and the 99th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Charleston County?
The three highest-rated hazards are Coastal Flood (Very High, $36M EAL), Hurricane (Very High, $281M EAL), Earthquake (High, $118M EAL). These account for most of the county's expected annual losses.
How does Charleston County compare to other South Carolina counties?
Charleston County ranks #1 of 46 South Carolina counties for overall natural disaster risk, with a high rating.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Charleston County's $500M EAL is a statistical average, not a guarantee for any specific year or address.