Chester County, South Carolina Natural Disaster Risk
FEMA National Risk Index assessment · SC
LowComposite Risk Score
National percentile: 43th
Chester County faces low composite natural disaster risk (NRI Risk Index score 43.2, 43th national percentile), driven primarily by ice storm and lightning exposure. Expected annual loss across all 18 hazard types is $11M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Chester County is low, with a National Risk Index score of 43.2 out of 100 — placing it in the 43rd national percentile and below the national average for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in ice storm (freezing rain that coats surfaces in heavy, damaging ice) at High risk — $394K in expected annual loss and about 1.93 events per year; lightning (electrical discharges from storms that ignite fires and cause casualties) at Medium risk — $498K in expected annual loss and about 53.15 events per year; and tornado (violently rotating columns of air capable of catastrophic local damage) at Medium risk — $2M in expected annual loss and about 0.41 events per year. Across all hazards, FEMA estimates $11M in expected annual loss for a population of 32K.
Beyond physical exposure, Chester County has a high 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). That combination — a more vulnerable population with limited resilience — can amplify the human cost of any given event.
History supports the rating: Chester County has received 23 federal disaster declarations since 1977, including 12 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, Chester County ranks #39 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Ice Storm | High | 1.93 / yr | $394K |
| Lightning | Medium | 53.15 / yr | $498K |
| Tornado | Medium | 0.41 / yr | $2M |
| Earthquake | Low | 0.00 / yr | $690K |
| Cold Wave | Medium | 0.21 / yr | $1M |
| Strong Wind | Medium | 4.65 / yr | $653K |
| Hurricane | Low | 0.10 / yr | $249K |
| Wildfire | Very Low | 0.00 / yr | $28K |
| Riverine Flood | Low | 0.39 / yr | $4M |
| Landslide | Very Low | 0.75 / yr | $579 |
| Heat Wave | Low | 3.05 / yr | $194K |
| Drought | Low | 26.64 / yr | $57K |
| Hail | Very Low | 4.90 / yr | $94K |
| Winter Weather | Very Low | 3.68 / yr | $15K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Chester County has received 23 federal disaster declarations since 1977, most recently Severe Winter Storm in January 2026. Most frequent causes: Hurricane (12), Severe Storm (3), Tropical Storm (2).
| Declared | Type | Disaster |
|---|---|---|
| January 2026 | Winter Storm | Severe Winter Storm |
| September 2024 | Hurricane | Hurricane Helene |
| 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 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| March 2020 | Biological | Covid-19 |
Showing the 10 most recent of 23 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Chester County?
Chester County has a composite FEMA National Risk Index score of 43.2 out of 100, placing it in the Low category and the 43th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Chester County?
The three highest-rated hazards are Ice Storm (High, $394K EAL), Lightning (Medium, $498K EAL), Tornado (Medium, $2M EAL). These account for most of the county's expected annual losses.
How does Chester County compare to other South Carolina counties?
Chester County ranks #39 of 46 South Carolina counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Chester County had?
FEMA records 23 federal disaster declarations for Chester County since 1977, most often 12 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. Chester County's $11M EAL is a statistical average, not a guarantee for any specific year or address.