Charleston County, South Carolina Natural Disaster Risk
FEMA National Risk Index assessment · SC
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
Risk Overview
FEMA's National Risk Index rates Charleston County at high composite risk, with a National Risk Index score of 98.6 out of 100 — placing it in the 99th national percentile and in the upper tier of natural-disaster risk nationally. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Charleston County's expected losses come from coastal flood (seawater inundation from storm surge, high tides, and rising sea levels) at Very High risk — $36M in expected annual loss and about 3.65 events per year; hurricane (tropical cyclones bringing extreme wind, rain, and storm surge) at Very High risk — $281M in expected annual loss and about 0.34 events per year; and earthquake (ground shaking from sudden movement along geologic faults) at High risk — $118M in expected annual loss and about 0.01 events per year. Across all hazards, FEMA estimates $500M in expected annual loss for a population of 408K.
Beyond physical exposure, Charleston County has a low social vulnerability rating (how susceptible the population is to harm) and a very high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
The federal record bears this out: Charleston County has received 27 federal disaster declarations since 1977, including 16 for hurricane events and 3 for severe storm events. The most recent was Severe Winter Storm (winter storm), declared in January 2026.
Among 46 South Carolina counties, Charleston County ranks #1 for overall natural disaster risk.
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 |
Disaster History
Charleston County has received 27 federal disaster declarations since 1977, most recently Severe Winter Storm in January 2026. Most frequent causes: Hurricane (16), Severe Storm (3), Tropical Storm (2).
| Declared | Type | Disaster |
|---|---|---|
| January 2026 | Winter Storm | Severe Winter Storm |
| September 2024 | Tropical Storm | Hurricane Helene |
| August 2024 | Tropical Storm | Hurricane Debby |
| August 2023 | Hurricane | Hurricane Idalia |
| November 2022 | Hurricane | Hurricane Ian |
| September 2022 | Hurricane | Hurricane Ian |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| September 2019 | Hurricane | Hurricane Dorian |
| September 2019 | Hurricane | Hurricane Dorian |
Showing the 10 most recent of 27 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
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.
How many federally declared disasters has Charleston County had?
FEMA records 27 federal disaster declarations for Charleston County since 1977, most often 16 for hurricane events and 3 for severe storm events. The most recent was Severe Winter Storm, declared in January 2026.
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.