Dorchester County, South Carolina Natural Disaster Risk
FEMA National Risk Index assessment · SC
MediumComposite Risk Score
National percentile: 94th
Dorchester County faces medium composite natural disaster risk (NRI Risk Index score 93.7, 94th national percentile), driven primarily by earthquake and hurricane exposure. Expected annual loss across all 18 hazard types is $176M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Dorchester County is medium, with a National Risk Index score of 93.7 out of 100 — placing it in the 94th national percentile and near the national midpoint for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Dorchester County's expected losses come from earthquake (ground shaking from sudden movement along geologic faults) at Medium risk — $58M in expected annual loss and about 0.01 events per year; hurricane (tropical cyclones bringing extreme wind, rain, and storm surge) at High risk — $84M in expected annual loss and about 0.31 events per year; and ice storm (freezing rain that coats surfaces in heavy, damaging ice) at High risk — $658K in expected annual loss and about 1.09 events per year. Across all hazards, FEMA estimates $176M in expected annual loss for a population of 161K.
Beyond physical exposure, Dorchester County has a very low social vulnerability rating (how susceptible the population is to harm) and a medium community resilience rating (its capacity to prepare for and recover from disasters). Both measures sit toward the lower end, indicating relatively modest population sensitivity.
The county's disaster history tells the same story: Dorchester County has received 26 federal disaster declarations since 1989, including 15 for hurricane events and 3 for tropical storm events. The most recent was Severe Winter Storm (winter storm), declared in January 2026.
Among 46 South Carolina counties, Dorchester County ranks #6 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Earthquake | Medium | 0.01 / yr | $58M |
| Hurricane | High | 0.31 / yr | $84M |
| Ice Storm | High | 1.09 / yr | $658K |
| Lightning | High | 66.11 / yr | $1M |
| Wildfire | Low | 0.00 / yr | $454K |
| Riverine Flood | Medium | 1.39 / yr | $23M |
| Tornado | Medium | 0.32 / yr | $4M |
| Heat Wave | Low | 8.91 / yr | $1M |
| Winter Weather | Medium | 1.05 / yr | $149K |
| Cold Wave | Medium | 0.69 / yr | $2M |
| Coastal Flood | Low | 3.50 / yr | $542K |
| Hail | Low | 3.05 / yr | $273K |
| Drought | Very Low | 15.41 / yr | $22K |
| Strong Wind | Low | 3.21 / yr | $204K |
| Landslide | Very Low | 0.16 / yr | $66 |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Dorchester County has received 26 federal disaster declarations since 1989, most recently Severe Winter Storm in January 2026. Most frequent causes: Hurricane (15), Tropical Storm (3), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| January 2026 | Winter Storm | Severe Winter Storm |
| September 2024 | Tropical Storm | Tropical Storm Debby |
| 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 |
Showing the 10 most recent of 26 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Dorchester County?
Dorchester County has a composite FEMA National Risk Index score of 93.7 out of 100, placing it in the Medium category and the 94th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Dorchester County?
The three highest-rated hazards are Earthquake (Medium, $58M EAL), Hurricane (High, $84M EAL), Ice Storm (High, $658K EAL). These account for most of the county's expected annual losses.
How does Dorchester County compare to other South Carolina counties?
Dorchester County ranks #6 of 46 South Carolina counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Dorchester County had?
FEMA records 26 federal disaster declarations for Dorchester County since 1989, most often 15 for hurricane events and 3 for tropical 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. Dorchester County's $176M EAL is a statistical average, not a guarantee for any specific year or address.